Form S-3 - Registration statement under Securities Act of 1933 (2024)

Asfiled with the Securities and Exchange Commission on June 13, 2024

RegistrationNo. 333-

UNITEDSTATES

SECURITIESAND EXCHANGE COMMISSION

WASHINGTON,D.C. 20549

FORMS-3

REGISTRATIONSTATEMENT UNDER THESECURITIES ACT OF 1933

NioCorpDevelopments Ltd.

(Exactname of registrant as specified in its charter)

Approximatedate of commencement of proposed sale to the public:From time to time after the effectiveness of this registration statement.

If the only securities being registered onthis Form are being offered pursuant to dividend or interest reinvestment plans, please check the following box: ¨

If any of the securities being registered onthis Form are to be offered on a delayed or continuous basis pursuant to Rule 415 under the Securities Act of 1933, other than securitiesoffered only in connection with dividend or interest reinvestment plans, check the following box: x

If this Form is filed to register additionalsecurities for an offering pursuant to Rule 462(b) under the Securities Act, please check the following box and list the Securities Actregistration statement number of the earlier effective registration statement for the same offering. ¨

If this Form is a post-effective amendmentfiled pursuant to Rule 462(c) under the Securities Act, check the following box and list the Securities Act registration statement numberof the earlier effective registration statement for the same offering. ¨

If this Form is a registration statement pursuantto General Instruction I.D. or a post-effective amendment thereto that shall become effective upon filing with the Commission pursuantto Rule 462(e) under the Securities Act, check the following box. ¨

If this Form is a post-effective amendmentto a registration statement filed pursuant to General Instruction I.D. filed to register additional securities or additional classes ofsecurities pursuant to Rule 413(b) under the Securities Act, check the following box. ¨

Indicate by check mark whether the registrantis a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company.See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company”and “emerging growth company” in Rule 12b-2 of the Exchange Act.

Ifan emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period forcomplying with any new or revised financial accounting standards pursuant to Section 7(a)(2)(B) of the Securities Act.☐

Theregistrant hereby amends this registration statement on such date or dates as may be necessary to delay its effective date untilthe registrant shall file a further amendment which specifically states that this registration statement shall thereafter becomeeffective in accordance with Section 8(a) of the Securities Act of 1933 or until the registration statement shall become effectiveon such date as the Securities and Exchange Commission, acting pursuant to said Section 8(a), may determine.

The information in this prospectusis not complete and may be changed. We may not sell these securities until the registration statement filed with the Securities and ExchangeCommission is effective. This prospectus is not an offer to sell these securities and it is not soliciting an offer to buy these securitiesin any state where the offer or sale is not permitted.

SUBJECT TO COMPLETION DATED JUNE 13,2024

PROSPECTUS

NioCorp Developments Ltd.

$200,000,000

Common Shares

Common Share Purchase Warrants

Units

We may offer and sell,from time to time, common shares, without par value (“Common Shares”), or Common Share purchase warrants (“Warrants”),as well as units that include any of these securities, or any combination thereof. We may sell any combination of these securities inone or more offerings with an aggregate offering price of up to $200,000,000.

This prospectus describesthe general manner in which the securities listed above may be offered and sold. The specific manner in which such securities may be offeredand sold will be described in one or more prospectus supplements. You should carefully read this prospectus and any accompanying prospectussupplement, together with the documents we incorporate by reference, before you invest in our securities.

We may sell securitiesdirectly or to or through underwriters or dealers, and also to other purchasers or through agents. The names of any underwriters or agentsthat are included in a sale of such securities to you, and any applicable commissions or discounts, will be stated in an accompanyingprospectus supplement.

Our Common Shares trade on The Nasdaq Global Marketunder the symbol “NB.” On June 12, 2024, the last reported sale price of our Common Shares on The Nasdaq Global Market was$2.14 per Common Share.

Investing in our securities involves a high degreeof risk. See “Risk Factors” beginning on page 2 of this prospectus.

Neither the Securities and Exchange Commissionnor any state securities commission has approved or disapproved of the securities or determined if this prospectus is truthful or complete.Any representation to the contrary is a criminal offense.

The date of this prospectus is         .

Table ofContents

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About This Prospectus

This prospectus is partof a registration statement on Form S-3 that we filed with the Securities and Exchange Commission (the “SEC”) using a “shelf”registration process. The Company may offer and sell from time to time any combination of the securitiesdescribed in this prospectus in one or more offerings in amounts, at prices and on terms that we determine at the time of the offering,with an aggregate offering price of up to $200,000,000. This prospectus provides you with a general description of the securities we mayoffer.Each time we offer securities under this prospectus, we will provide a prospectus supplement that will contain specific informationabout the type or series of securities offered and the terms of that offering.

This prospectus may not be used to consummate asale of securities unless it is accompanied by a prospectus supplement.

You should rely only on the information provided inthis prospectus, as well as the information incorporated by reference into this prospectus and any applicable prospectus supplement. Wehave not authorized anyone to provide you with different information. We have not authorized anyone to provide you with any informationor to make any representations other than those contained in this prospectus or any applicable prospectus supplement or any free writingprospectuses prepared by or on behalf of us or to which we have referred you. We do not take responsibility for, and can provide no assuranceas to the reliability of, any other information that others may give you. You should not assume that the information in this prospectusor any applicable prospectus supplement is accurate as of any date other than the date of the applicable document. Since the date of thisprospectus and the documents incorporated by reference into this prospectus, our business, financial condition, results of operationsand prospects may have changed. We will not make an offer to sell these securities in any jurisdiction where the offer or sale is notpermitted.

We may also provide a prospectus supplement or post-effectiveamendment to the registration statement of which this prospectus is a part to add information to, or update or change information containedin, this prospectus and the registration statement of which this prospectus is a part. You should read this prospectus and any applicableprospectus supplement or post-effective amendment to the registration statement of which this prospectus is a part together with the additionalinformation to which we refer you in the sections of this prospectus entitled “Where You Can Find More Information” and “InformationIncorporated by Reference.”

Unless we state otherwise or the context otherwiserequires, the terms “we,” “us,” “our,” “our business” “NioCorp,” “theCompany” and similar references refer to NioCorp Developments Ltd. and its consolidated subsidiaries.

Unless we state otherwise or the context otherwiserequires, the term “ECRC” refers to Elk Creek Resources Corp. (formerly known as GX Acquisition Corp. II), a Delaware corporationand a majority-owned subsidiary of NioCorp, as the surviving entity of the mergers that occurred on March 17, 2023, as part of the Transactions(as defined herein), and the term “GXII” refers to GX Acquisition Corp. II, a Delaware corporation, as it existed prior tothe closing of the Transactions.

This prospectus containsour registered and unregistered trademarks and service marks, as well as trademarks and service marks of third parties. Solely for convenience,these trademarks and service marks are referenced without the ®, ™ or similar symbols, but such references are not intendedto indicate, in anyway, that we will not assert, to the fullest extent under applicable law, our rights to these trademarks and servicemarks. All brand names, trademarks and service marks appearing in this prospectus are the property of their respective holders.

Where You Can Find More Information

This prospectus is part of a registration statementon Form S-3 that we filed with the SEC under the Securities Act of 1933 (the “Securities Act”) and does not contain all theinformation set forth or incorporated by reference in the registration statement. Whenever a reference is made in this prospectus to anyof our contracts, agreements or other documents, the reference may not be complete and you should refer to the exhibits that are a partof the registration statement of which this prospectus is a part or the exhibits to the reports or other documents incorporated by referenceinto this prospectus for a copy of such contract, agreement or other document. You may obtain copies of the registration statement andits exhibits via the SEC’s EDGAR database.

We file annual, quarterly and current reports, proxystatements and other information with the SEC under the Securities Exchange Act of 1934 (the “Exchange Act”). The SEC maintainsa website that contains reports, proxy and information statements and other information regarding issuers, including us, that file electronicallywith the SEC. You may obtain documents that we file with the SEC at www.sec.gov.

We make available, freeof charge, on our website atwww.niocorp.com, our annual reports on Form 10-K, quarterly reports on Form 10-Q, current reportson Form 8-K, proxy statements and amendments to those reports and statements as soon as reasonably practicable after they are filed withthe SEC. We do not incorporate the information on or accessible through any website into this prospectus or any prospectus supplement,and you should not consider any information on, or that can be accessed through, any website as part of this prospectus or any prospectussupplement (other than those filings with the SEC that we specifically incorporate by reference into this prospectus or any prospectussupplement). Our website address and the SEC’s website address are included in this prospectus as inactive textual references only.

Information Incorporated by Reference

SEC rules permit us to incorporate information byreference into this prospectus and any applicable prospectus supplement. This means that we can disclose important information to youby referring you to another document filed separately with the SEC. The information incorporated by reference is considered to be partof this prospectus and any applicable prospectus supplement, except for information superseded by information contained in this prospectusor the applicable prospectus supplement itself or in any subsequently filed incorporated document. This prospectus and any applicableprospectus supplement incorporate by reference the documents set forth below that we have previously filed with the SEC, other than informationin such documents that is deemed to be furnished and not filed. These documents contain important information about us and our businessand financial condition. Any report or information within any of the documents referenced below that is furnished, but not filed, shallnot be incorporated by reference into this prospectus:

We also incorporate by reference any future filingsmade by us with the SEC under Section 13(a), 13(c), 14 or 15(d) of the Exchange Act (excluding any information furnished to, rather thanfiled with, the SEC), including after the date of the initial registration statement of which this prospectus is a part and prior to effectivenessof the registration statement, and after effectiveness of the registration statement and prior to the termination of the offering of thesecurities made by this prospectus. Information in such future filings updates and supplements the information provided in this prospectus.Any statements in any such future filings will automatically be deemed to modify and supersede any information in any document we previouslyfiled with the SEC that is incorporated or deemed to be incorporated herein by reference to the extent that statements in the later fileddocument modify or replace such earlier statements.

You may request a copy of these filings, at no cost,by writing or calling us at the following address or telephone number below:

NioCorp DevelopmentsLtd.

7000 South Yosemite Street,Suite 115

Centennial, Colorado 80112

(720) 334-7066

Attn: Corporate Secretary

Those copies will not include exhibits, unless theexhibits have specifically been incorporated by reference in this document or you specifically request them.

Risk Factors

Investing in our securities involves a high degreeof risk. Prior to making a decision about investing in our securities, you should carefully consider the specific risk factors discussedunder the heading “Risk Factors” in our most recent Annual Report on Form 10-K and in our most recent QuarterlyReports on Form 10-Q, which are or will be incorporated herein by reference and may be amended, supplemented or supersededfrom time to time by other reports we file with the SEC in the future. You should also refer to the other information in this prospectusand the applicable prospectus supplement, including our financial statements and the related notes incorporated by reference in this prospectus.The risks and uncertainties we have described are not the only risks we face. Additional risks and uncertainties not presently known tous or that we currently deem immaterial may also affect our operations. If any of these risks actually occurs, our business, results ofoperations and financial condition could suffer and could result in a complete loss of your investment.

Cautionary Note Regarding Forward-Looking Statements

This prospectusand the other documents incorporated by reference into this prospectus contain or may contain “forward-looking statements”within the meaning of Section 27A of the Securities Act and Section 21E of the Exchange Act, and “forward-looking information”within the meaning of applicable Canadian securities legislation (collectively, “forward-looking statements”). Such forward-lookingstatements concern our anticipated results and developments in the operations of the Company in future periods, planned exploration activities,the adequacy of the Company’s financial resources, and other events or conditions that may occur in the future.

Forward-lookingstatements have been based upon our current business and operating plans, as approved by the Company’s Board of Directors, and mayinclude statements regarding the anticipated benefits of the transactions contemplated by the Business Combination Agreement (the “BusinessCombination Agreement”), dated September 25, 2022, between NioCorp, GXII, Big Red Merger Sub Ltd, a Delaware corporation and a direct,wholly owned subsidiary of the Company (the “Transactions”), including NioCorp’s ability to access the full amount ofthe expected net proceeds of the Standby Equity Purchase Agreement, dated January 26, 2023 (as amended, the “Yorkville Equity FacilityFinancing Agreement”), between NioCorp and YA II PN, Ltd. (“YA”), a fund managed by Yorkville Advisors Global, LP, throughApril 1, 2026; NioCorp’s ability to receive a final commitment of financing from the Export-Import Bank of the United States (“EXIM”);anticipated benefits of the listing of the Common Shares on Nasdaq; the financial and business performance of NioCorp; NioCorp’santicipated results and developments in the operations of NioCorp in future periods; NioCorp’s planned exploration and developmentactivities; the adequacy of NioCorp’s financial resources; NioCorp’s ability to secure sufficient project financing to completeconstruction and commence operation of the Elk Creek Project; NioCorp’s expectation and ability to produce niobium, scandium, andtitanium at the Elk Creek Project; NioCorp’s plans to produce and supply specific products and market demand for those products;the Elk Creek Project’s ability to produce multiple critical metals; NioCorp’s expectation that the process improvements resultingfrom previously completed recovery process improvement testing could lead to greater efficiencies and cost savings in the Elk Creek Project;the Elk Creek Project’s projected ore production and mining operations over its expected mine life; the completion and content ofan updated technical report for the Elk Creek Project; the completion of technical and economic analyses on the potential addition ofmagnetic rare earth oxides to NioCorp’s planned product suite; anticipated benefits of the electrification of access to the ElkCreek Project mine site; the exercise of options to purchase additional land parcels; the execution of contracts with engineering, procurementand construction companies; the advancement of offtake discussions with potential customers; NioCorp’s ongoing evaluation of theimpact of inflation, supply chain issues and geopolitical unrest on the Elk Creek Project’s economic model; and the creation offull time and contract construction jobs over the construction period of the Elk Creek Project.

Forward-lookingstatements are frequently, but not always, identified by words such as “expects,” “anticipates,” “believes,”“intends,” “estimates,” “potential,” “possible,” and similar expressions, or statementsthat events, conditions, or results “will,” “may,” “could,” or “should” (or the negativeand grammatical variations of any of these terms) occur or be achieved. Any statements that express or involve discussions with respectto predictions, expectations, beliefs, plans, projections, objectives, assumptions, or future events or performance (often, but not always,using words or phrases such as “expects” or “does not expect,” “is expected,” “anticipates”or “does not anticipate,” “plans,” “estimates,” or “intends,” or stating that certainactions, events, or results “may,” “could,” “would,” “might,” or “will” betaken, occur or be achieved) are not statements of historical fact and may be forward-looking statements. Such forward-looking statementsreflect the Company’s current views with respect to future events and are subject to certain known and unknown risks, uncertainties,and assumptions. Many factors could cause actual results, performance, or achievements to be materially different from any future results,performance, or achievements that may be expressed or implied by such forward-looking statements, including, among others, risks relatedto the following: NioCorp’s ability to recognize the anticipated benefits of the Transactions, including NioCorp’s abilityto access the full amount of the expected net proceeds under the Yorkville Equity Facility Financing Agreement through April 1, 2026;unexpected costs related to the Transactions; the outcome of any legal proceedings that may be instituted against NioCorp following closingof the Transactions; NioCorp’s ability to receive a final commitment of financing from EXIM on the anticipated timeline, on acceptableterms, or at all; NioCorp’s ability to continue to meet Nasdaq listing standards; NioCorp’s ability to operate as a goingconcern; risks relating to the Common Shares, including price volatility, lack of dividend payments and dilution or the perception ofthe likelihood any of the foregoing; NioCorp’s requirement of significant additional capital; the extent to which NioCorp’slevel of indebtedness and/or the terms contained in agreements governing NioCorp’s indebtedness or the Yorkville Equity FacilityFinancing Agreement may impair NioCorp’s ability to obtain additional financing, on acceptable terms, or at all; covenants containedin agreements with NioCorp’s secured creditors that may affect its assets; NioCorp’s limited operating history; NioCorp’shistory of losses; the material weaknesses in NioCorp’s internal control over financial reporting, NioCorp’s efforts to remediatesuch material weaknesses and the timing of remediation; the possibility that NioCorp may qualify as a passive foreign investment company(“PFIC”) under the U.S. Internal Revenue Code of 1986, as amended (the “Code”); the potential that the Transactionscould result in NioCorp becoming subject to materially adverse U.S. federal income tax consequences as a result of the application ofSection 7874 and related sections of the Code; cost increases for NioCorp’s exploration and, if warranted, development projects;a disruption in, or failure of, NioCorp’s information technology systems, including those related to cybersecurity; equipment andsupply shortages; variations in the market demand for, and prices of, niobium, scandium, titanium and rare earth products; current andfuture offtake agreements, joint ventures, and partnerships; NioCorp’s ability to attract qualified management; the effects ofglobal health crises on NioCorp’s business plans, financial condition and liquidity; estimates of mineral resources and reserves;mineral exploration and production activities; feasibility study results; the results of metallurgical testing; the results of technologicalresearch; changes in demand for and price of commodities (such as fuel and electricity) and currencies; competition in the mining industry;changes or disruptions in the securities markets; legislative, political or economic developments, including changes in federal and/orstate laws that may significantly affect the mining industry; the impacts of climate change, as well as actions taken or required bygovernments related to strengthening resilience in the face of potential impacts from climate change; the need to obtain permits andcomply with laws and regulations and other regulatory requirements; the timing and reliability of sampling and assay data; the possibilitythat actual results of work may differ from projections/expectations or may not realize the perceived potential of NioCorp’s projects;risks of accidents, equipment breakdowns, and labor disputes or other unanticipated difficulties or interruptions; the possibility ofcost overruns or unanticipated expenses in development programs; operating or technical difficulties in connection with exploration,mining, or development activities; the management of the water balance at the Elk Creek Project site; land reclamation requirements relatedto the Elk Creek Project; the speculative nature of mineral exploration and development, including the risks of diminishing quantitiesof grades of reserves and resources; claims on the title to NioCorp’s properties; potential future litigation; and NioCorp’slack of insurance covering all of NioCorp’s operations.

Shouldone or more of these risks or uncertainties materialize, or should underlying assumptions prove incorrect, actual results may vary materiallyfrom those described herein. This list is not exhaustive of the factors that may affect any of the Company’s forward-looking statements.Forward-looking statements are statements about the future and are inherently uncertain, and actual achievements of the Company or otherfuture events or conditions may differ materially from those reflected in the forward-looking statements due to a variety of risks, uncertainties,and other factors, including without limitation those discussed under Part I, Item 1A. “Risk Factors” contained in our mostrecent Annual Report on Form 10-K, and Part II, Item 1A. “Risk Factors” contained in our subsequent Quarterly Reports on Form10-Q, as well as any amendments thereto, which are incorporated by reference into this prospectus and the applicable prospectus supplementin their entirety, together with other information in this prospectus and the applicable prospectus supplement and the documents incorporatedby reference herein and therein. See the sections of this prospectus entitled “Where You Can Find More Information” and “InformationIncorporated by Reference.”

The Company’sforward-looking statements contained in this prospectus are based on the beliefs, expectations, and opinions of management as of the dateof this prospectus. The Company does not assume any obligation to update forward-looking statements if circ*mstances or management’sbeliefs, expectations, or opinions should change, except as required by law. For the reasons set forth above, investors should not attributeundue certainty to, or place undue reliance on, forward-looking statements.

Use of Proceeds

Unless the applicableprospectus supplement states otherwise, we expect to use the net proceeds of the sale of the securities offered by this prospectus forworking capital and general corporate purposes, including to advance our efforts to launch construction of the Elk Creek Project and moveit to commercial operation.

As of the date of this prospectus,we have not identified as probable any specific material proposed uses of these proceeds. If, as of the date of any prospectus supplement,we have identified any such uses, we will describe them in the prospectus supplement. Pending any such uses, we may temporarily investthe net proceeds.

Description of Capital Stock

Common Shares

The authorized capitalof the Company consists of an unlimited number of Common Shares without par value, of which 37,576,647 were issued and outstanding asof June 12, 2024. The holders of Common Shares are entitled to receive notice of and attend all meetings of shareholders, with each CommonShare held entitling the holder to one vote on any resolution to be passed at such shareholder meetings. The holders of Common Sharesare entitled to dividends if, as and when declared by the Company’s Board of Directors. The Common Shares are entitled, upon liquidation,dissolution, or winding up of NioCorp, to receive the remaining assets of NioCorp available for distribution to shareholders. There areno pre-emptive, conversion, or redemption rights attached to the Common Shares.

ExchangeControls

There are no governmentallaws, decrees, or regulations in Canada that restrict the export or import of capital, including foreign exchange controls, or that affectthe remittance of dividends, interest or other payments to non-resident holders of the securities of NioCorp, other than as discussedbelow and Canadian withholding tax. See “—Certain Canadian Federal Income Tax Considerations for U.S. Residents.”

Certain Canadian Federal Income Tax Considerations for U.S.Residents

The following generallysummarizes certain Canadian federal income tax consequences generally applicable under the Income Tax Act (Canada) and the regulationsenacted thereunder (collectively, the “Canadian Tax Act”) and the Canada-United States Tax Convention (1980) (the “Convention”)to the holding and disposition of Common Shares.

Comment is restrictedto holders of Common Shares each of whom, at all material times for the purposes of the Canadian Tax Act and the Convention, (i) is residentsolely in the United States for tax purposes, (ii) is a “qualifying person” under and entitled to the benefits of the Convention,(iii) holds all Common Shares as capital property, (iv) holds no Common Shares that are “taxable Canadian property” (as definedin the Canadian Tax Act) of the holder, (v) deals at arm’s length with and is not affiliated with the Company, (vi) does not andis not deemed to use or hold any Common Shares in a business carried on in Canada, (vii) is not an insurer that carries on business inCanada and elsewhere, (viii) is not an “authorized foreign bank” (as defined in the Canadian Tax Act), and (ix) has not enteredinto a “derivative forward agreement” (as defined in the Canadian Tax Act) with respect to the Common Shares (each such holder,a “U.S. Resident Holder”).

Certain U.S.-residententities that are fiscally transparent for United States federal income tax purposes (including limited liability companies) may not inall circ*mstances be entitled to the benefits of the Convention. Members of or holders of an interest in such an entity that holds CommonShares should consult their own tax advisers regarding the extent, if any, to which the benefits of the Convention will apply to the entityin respect of its Common Shares.

Generally, a U.S. ResidentHolder’s Common Shares will be considered to be capital property of such holder provided that the U.S. Resident Holder is not atrader or dealer in securities, did not acquire, hold, or dispose of the Common Shares in one or more transactions considered to be anadventure or concern in the nature of trade (i.e., speculation), and does not hold the Common Shares in the course of carryingon a business.

Thissummary is based on the current provisions of the Canadian Tax Act and the Convention in effect as of the date prior to the date hereof,all specific proposals to amend the Canadian Tax Act and Convention publicly announced by or on behalf of the Minister of Finance (Canada)prior to the date hereof, and the current published administrative policies and assessing practices of the Canada Revenue Agency (the“CRA”). It is assumed that all such amendments will be enacted as currently proposed, and that there will be no other materialchange to any applicable law or administrative policy or assessing practice, whether by way of judicial, legislative or governmental decisionor action, although no assurance can be given in these respects. This summary is not exhaustive of all possible Canadian federal incometax considerations. Except as otherwise expressly provided, this summary does not take into account any provincial, territorial, or foreigntax considerations, which may differ materially from those set out herein.

This summary isof a general nature only, is not exhaustive of all possible Canadian federal income tax considerations, and is not intended to be andshould not be construed as legal or tax advice to any particular U.S. Resident Holder. U.S. Resident Holders are urged to consult theirown tax advisers for advice with respect to their particular circ*mstances. The discussion below is qualified accordingly.

Generally, a U.S. ResidentHolder’s Common Shares will not constitute “taxable Canadian property” of such holder at a particular time at whichthe Common Shares are listed on a “designated stock exchange” (which currently includes Nasdaq) unless both of the followingconditions are concurrently met:

Common Shares may alsobe deemed to be “taxable Canadian property” in certain circ*mstances set out in the Canadian Tax Act.

A U.S. Resident Holderwho disposes or is deemed to dispose of one or more Common Shares generally should not thereby incur any liability for Canadian federalincome tax in respect of any capital gain arising as a consequence of the disposition.

A U.S. Resident Holderto whom the Company pays or credits or is deemed to pay or credit a dividend on such holder’s Common Shares will be subject to Canadianwithholding tax, and the Company will be required to withhold the tax from the dividend and remit it to the CRA for the holder’saccount. The rate of withholding tax under the Canadian Tax Act is 25% of the gross amount of the dividend, but should generally be reducedunder the Convention to 15% (or, if the U.S. Resident Holder is a company which is the beneficial owner of at least 10% of the votingstock of the Company, 5%) of the gross amount of the dividend. For this purpose, a company that is a resident of the United States forpurposes of the Canadian Tax Act and the Convention and is entitled to the benefits of the Convention shall be considered to own the votingstock of the Company owned by an entity that is considered fiscally transparent under the laws of the United States and that is not aresident of Canada, in proportion to such company’s ownership interest in that entity.

Competition Act

Limitationson the ability to acquire and hold Common Shares may be imposed by the Competition Act (Canada). This legislation permits the Commissionerof Competition of Canada (the “Commissioner”) to review any acquisition of a significant interest in the Company. This legislationgrants the Commissioner jurisdiction to challenge such an acquisition before the Canadian Competition Tribunal if the Commissioner believesthat it would, or would be likely to, result in a substantial lessening or prevention of competition in any market in Canada.

Investment CanadaAct

The InvestmentCanada Act subjects an acquisition of control of a company by a non-Canadian to government review if the enterprise value of such company,as calculated pursuant to the legislation, exceeds a threshold amount. A reviewable acquisition may not proceed unless the relevant ministeris satisfied that the investment is likely to result in a net benefit to Canada. Under the national-security-review regime in the InvestmentCanada Act, review on a discretionary basis may also be undertaken by the federal government in respect of a broad range of investmentsby a non-Canadian. No financial threshold applies to a national security review. The relevant test is whether such investment by a non-Canadiancould be “injurious to national security.”

NioCorp Assumed Warrants

In connection with the closing of the Transactions(the “Closing”), pursuant to the Business Combination Agreement, the Company assumed the Warrant Agreement, dated as of March17, 2021 (the “GXII Warrant Agreement”), by and between GXII and Continental Stock Transfer & Trust Company (“CST”),as warrant agent, and each share purchase warrant of GXII thereunder (the “GXII Warrants”) that was issued and outstandingimmediately prior to March 17, 2023 was converted into one Warrant (the “NioCorp Assumed Warrants”) pursuant to the assignment,assumption and amendment agreement to the GXII Warrant Agreement, dated March 17, 2023 (the GXII Warrant Agreement, as so amended, the“NioCorp Assumed Warrant Agreement”), among NioCorp, GXII, CST, as existing warrant agent, and Computershare Inc. and itsaffiliate Computershare Trust Company, N.A., together as successor warrant agent (the “NioCorp Assumed Warrant Agent”). Inconnection with the Closing, NioCorp issued (a) 9,999,959 public NioCorp Assumed Warrants in respect of the GXII Warrants that were publiclytraded prior to the Closing and (b) 5,666,667 NioCorp Assumed Warrants to GX Sponsor II LLC (the “Sponsor”) in respect ofthe GXII Warrants that it held prior to the Closing, which NioCorp Assumed Warrants were subsequently distributed by the Sponsor to itsmembers in connection with the Closing.

Both the public NioCorp Assumed Warrants and the NioCorpAssumed Warrants issued to the Sponsor are subject to the terms of the NioCorp Assumed Warrant Agreement and are identical, with certainexceptions applicable to the NioCorp Assumed Warrants issued to the Sponsor for so long as such NioCorp Assumed Warrants are held by theSponsor, its members, or their respective affiliates and other permitted transferees. In accordance with the NioCorp Assumed Warrant Agreement,any NioCorp Assumed Warrants issued to the Sponsor that are held by someone other than the Sponsor, its members, or their respective affiliatesand other permitted transferees, are treated as public NioCorp Assumed Warrants.

Each NioCorp Assumed Warrant is exercisable on andafter April 16, 2023 until its expiration for 1.11829212 Common Shares at a price of $11.50 per 1.11829212 Common Shares (subject to adjustmentsfor stock splits, stock dividends, reorganizations, recapitalizations and the like). Under the terms of NioCorp Assumed Warrant Agreement,for so long as the NioCorp Assumed Warrants issued to the Sponsor are held by the Sponsor, its members, or their respective affiliatesand other permitted transferees, such holders have the right to elect to exercise those NioCorp Assumed Warrants on a cashless basis.For such NioCorp Assumed Warrants exercised on a cashless basis after the Closing, the holder will be entitled to pay the exercise pricefor those NioCorp Assumed Warrants by surrendering all or portion of the cash and/or Common Shares (valued at their fair market value)into which those NioCorp Assumed Warrants are exercisable as shall be elected by the holder. For this purpose, Common Shares so surrenderedwill be deemed to have a “fair market value” equal to the average reported last sale price of the Common Shares for the 10trading days ending on the third trading day prior to the date of exercise of the applicable NioCorp Assumed Warrants.

The NioCorp Assumed Warrants will expire at 5:00 p.m.,New York City time, on March 17, 2028 or earlier upon redemption or liquidation.

The Company will not be obligated to deliver anyCommon Shares pursuant to the exercise of a NioCorp Assumed Warrant and will have no obligation to settle such exercise unless a registrationstatement under the Securities Act with respect to the Common Shares underlying the NioCorp Assumed Warrants is then effective and aprospectus relating thereto is current, subject to the Company satisfying its obligations described below with respect to registration.No NioCorp Assumed Warrant will be exercisable and the Company will not be obligated to issue Common Shares upon exercise of a NioCorpAssumed Warrant unless Common Shares issuable upon such exercise have been registered, qualified or deemed to be exempt under the securitieslaws of the state of residence of the registered holder of the NioCorp Assumed Warrants. In the event that the conditions in the twoimmediately preceding sentences are not satisfied with respect to a NioCorp Assumed Warrant, the holder of such NioCorp Assumed Warrantwill not be entitled to exercise such NioCorp Assumed Warrant and such NioCorp Assumed Warrant may have no value and expire worthless.In no event will the Company be required to net cash settle any NioCorp Assumed Warrant.

The NioCorp Assumed Warrants, and the underlyingCommon Shares issuable upon the exercise thereof, were registered under the Securities Act pursuant to the Company’s registrationstatement on Form S-4, originally filed on November 7, 2022, as subsequently amended, which was declared effective by the SEC on February8, 2023. The ongoing registered offering of the Common Shares underlying the NioCorp Assumed Warrants is being conducted pursuant to theCompany’s registration statement on Form S-3, originally filed on April 14, 2023, as subsequently post-effectively amended to convertsuch registration statement to Form S-1, which was declared effective on October 30, 2023.

The Company will have the right to call the publicNioCorp Assumed Warrants for redemption at any time following the Closing Date:

The NioCorp Assumed Warrants issued to the Sponsorare not redeemable by the Company for so long as such NioCorp Assumed Warrants are held by the Sponsor, its members, or their respectiveaffiliates or other permitted transferees. In addition, the Company may not exercise its redemption right if the issuance of Common Sharesupon exercise of the NioCorp Assumed Warrants is not exempt from registration or qualification under applicable state blue sky laws orthe Company is unable to effect such registration or qualification.

If the Company calls the public NioCorp Assumed Warrantsfor redemption as described above, the Company will have the option to require any holder that wishes to exercise its public NioCorpAssumed Warrant to do so on a “cashless basis.” In determining whether to require all holders to exercise their public NioCorpAssumed Warrants on a “cashless basis,” the Company will consider, among other factors, its cash position, the number ofNioCorp Assumed Warrants that are outstanding and the dilutive effect on the Company’s shareholders of issuing the maximum numberof Common Shares issuable upon the exercise of the NioCorp Assumed Warrants. If the Company takes advantage of this option, all holdersof public NioCorp Assumed Warrants would pay the exercise price by surrendering their NioCorp Assumed Warrants for that number of CommonShares equal to the quotient obtained by dividing (x) the product of the number of Common Shares underlying the public NioCorp AssumedWarrants, multiplied by the difference between the exercise price of the NioCorp Assumed Warrants and the “fair market value”(defined below) by (y) the fair market value. The “fair market value” shall mean the average reported last sale price ofthe Common Shares for the 10 trading days ending on the third trading day prior to the date on which the notice of redemption is sentto the holders of public NioCorp Assumed Warrants. If the Company takes advantage of this option, the notice of redemption will containthe information necessary to calculate the number of Common Shares to be received upon exercise of the NioCorp Assumed Warrants, includingthe “fair market value” in such case. Requiring a cashless exercise in this manner will reduce the number of Common Sharesto be issued and thereby lessen the dilutive effect of a redemption of the public NioCorp Assumed Warrants. If the Company calls thepublic NioCorp Assumed Warrants for redemption and does not take advantage of this option, the Sponsor, its members, and their respectiveaffiliates and other permitted transferees would still be entitled to exercise their NioCorp Assumed Warrants for cash or on a cashlessbasis using the same formula described above that other NioCorp Assumed Warrant holders would have been required to use had all NioCorpAssumed Warrant holders been required to exercise their NioCorp Assumed Warrants on a cashless basis, as described in more detail below.

A holder of a NioCorp Assumed Warrant may notify theCompany in writing in the event it elects to be subject to a requirement that such holder will not have the right to exercise such NioCorpAssumed Warrant, to the extent that after giving effect to such exercise, such holder (together with such holder’s affiliates),to the NioCorp Assumed Warrant Agent’s actual knowledge, would beneficially own in excess of 4.9% or 9.8% (or such other amountas a holder may specify) of the Common Shares outstanding immediately after giving effect to such exercise.

The NioCorp Assumed Warrants have certain anti-dilutionand adjustments rights upon certain events.

The NioCorp Assumed Warrants may be exercised uponsurrender of the certificate representing such NioCorp Assumed Warrants on or prior to the expiration date at the offices of the NioCorpAssumed Warrant Agent, with the exercise form on the reverse side of such certificate completed and executed as indicated, accompaniedby full payment of the exercise price (or on a cashless basis, if applicable), by certified or official bank check payable to the orderof the NioCorp Assumed Warrant Agent or by wire transfer, for the number of NioCorp Assumed Warrants being exercised. The NioCorp AssumedWarrant holders will not have the rights or privileges of holders of Common Shares or any attendant voting rights until they exercisetheir NioCorp Assumed Warrants and receive Common Shares. After the issuance of Common Shares upon exercise of the NioCorp Assumed Warrants,each holder will be entitled to one (1) vote for each Common Share held of record on all matters to be voted on by NioCorp shareholders.

If, upon exercise of the NioCorp Assumed Warrants,a holder would be entitled to receive a fractional interest in a share, the Company will, upon exercise, round down to the nearest wholenumber of Common Shares to be issued to the NioCorp Assumed Warrant holder.

The NioCorp Assumed Warrants were issued in registeredform under the NioCorp Assumed Warrant Agreement. The NioCorp Assumed Warrant Agreement may be amended by the parties thereto withoutthe consent of any registered holder (i) for the purpose of curing any ambiguity, or curing, correcting or supplementing any mistake,or adding or changing any other provisions with respect to matters or questions arising under NioCorp Assumed Warrant Agreement as theparties may deem necessary or desirable and that the parties deem shall not adversely affect the interest of the registered holders ofthe NioCorp Assumed Warrants, and (ii) to provide for the delivery of such kind and amount of Common Shares or other securities or property(including cash) receivable upon a reclassification, reorganization, merger or consolidation, or upon a dissolution following any suchsale or transfer, that the holder of NioCorp Assumed Warrants would have received if such holder had exercised his, her or its NioCorpAssumed Warrants immediately prior to such event. All other modifications or amendments, including any amendment to increase the warrantprice or shorten the exercise period, shall require the vote or written consent of the registered holders of a majority of the then outstandingpublic NioCorp Assumed Warrants. Any amendment solely to the NioCorp Assumed Warrants issued to the Sponsor and that are held by the Sponsor,its members, or their respective affiliates or other permitted transferees, shall require the vote or written consent of a majority ofthe holders of the then outstanding NioCorp Assumed Warrants issued to the Sponsor.

Convertible Debentures

On January 26, 2023, NioCorp entered into the SecuritiesPurchase Agreement (the “Yorkville Convertible Debt Financing Agreement”) with YA. Pursuant to the Yorkville Convertible DebtFinancing Agreement, YA advanced a total amount of $15,360,000 to NioCorp in consideration of the issuance by NioCorp to YA of $16,000,000aggregate principal amount of convertible debentures (the “Convertible Debentures”) at the time of Closing (the “DebentureClosing”). As of June 12, 2024, there was $550,000 aggregate principal amount of the Convertible Debentures outstanding.

Each Convertible Debenture issued under the YorkvilleConvertible Debt Financing Agreement is an unsecured obligation of NioCorp, matures on September 17, 2024, which maturity may be extendedfor one six-month period in certain circ*mstances at the option of NioCorp, and incurs a simple interest rate obligation of 5.0% perannum (which will increase to 15.0% per annum upon the occurrence of an event of default). The outstanding principal amount of, accruedand unpaid interest, if any, on, and premium, if any, on the Convertible Debentures must be paid by NioCorp in cash when the same becomesdue and payable under the terms of the Convertible Debentures at their stated maturity, upon their redemption or otherwise.

Subject to certain limitations contained within theYorkville Convertible Debt Financing Agreement and the Convertible Debentures, including those as described below, holders of the ConvertibleDebentures will be entitled to convert the principal amount of, and accrued and unpaid interest, if any, on each Convertible Debenture,in whole or in part, from time to time over their term, into a number of Common Shares equal to the quotient of the principal amount andaccrued and unpaid interest, if any, being converted divided by the Conversion Price. The “Conversion Price” means, as ofany Conversion Date (as defined below) or other date of determination, the greater of (i) 90% of the average of the daily U.S. dollarvolume-weighted average price of the Common Shares on the principal U.S. market for the Common Shares as reported by Bloomberg FinancialMarkets during the five consecutive trading days immediately preceding the date on which the holder exercises its conversion right inaccordance with the requirements of the Yorkville Convertible Debt Financing Agreement (the “Conversion Date”) or other dateof determination, but not lower than the Floor Price (as defined below), and (ii) the five-day volume-weighted average price of the CommonShares on the TSX (or on the principal U.S. market if the majority of the trading volume and value of the Common Shares occurred on Nasdaqduring the relevant period) for the five consecutive trading days immediately prior to the Conversion Date or other date of determinationless the maximum applicable discount allowed by the TSX. The “Floor Price” means a price of $2.1435 per share, which is equalto the lesser of (a) 30% of the average of the daily volume-weighted average price of the Common Shares on the principal U.S. market forthe Common Shares as reported by Bloomberg Financial Markets during the five consecutive trading days immediately preceding the DebentureClosing and (b) 30% of the average of the volume-weighted average price of the Common Shares on the principal U.S. market for the CommonShares as reported by Bloomberg Financial Markets during the five consecutive trading days immediately following the Debenture Closing,subject to certain adjustments to give effect to any stock dividend, stock split, reverse stock split, recapitalization or similar event.

The terms of the Convertible Debentures restrict thenumber of Convertible Debentures that may be converted during each calendar month by YA at a Conversion Price below a fixed price equalto approximately $8.9422 (i.e., the quotient of $10.00 divided by 1.11829212 (being the number of Common Shares that were exchanged foreach share of GXII at the Closing, after giving effect to the reverse stock split at a ratio of 10-for-1 effectuated by each of NioCorpand ECRC on the date of Closing (the “Reverse Stock Split”))), subject to adjustment to give effect to any stock dividend,stock split, reverse stock split, recapitalization or similar event. The Convertible Debentures are subject to customary anti-dilutionadjustments.

The terms of the Convertible Debentures restrict theconversion of Convertible Debentures by YA if such a conversion would cause YA to exceed certain beneficial ownership thresholds in NioCorpor such a conversion would cause the aggregate number of Common Shares issued pursuant to the Yorkville Convertible Debt Financing Agreementto exceed the thresholds for issuance of Common Shares under the rules of Nasdaq, unless prior shareholder approval is obtained.

Financing Warrants

In conjunction with the Debenture Closing, NioCorpissued to YA pursuant to the Yorkville Convertible Debt Financing Agreement financing warrants (the “Financing Warrants”)to purchase 1,789,267 Common Shares, which is equal to the quotient of the principal amount of Convertible Debentures issued in such DebentureClosing divided by the “Exercise Price,” which is equal to approximately $8.9422 (i.e., the quotient of $10.00 divided by1.11829212 (being the number of Common Shares that were exchanged for each share of GXII at the Closing, after giving effect to the reversestock split at a ratio of 10-for-1 effectuated by each of NioCorp and ECRC on the Closing Date)), in each case, subject to adjustmentto give effect to any stock dividend, stock split, reverse stock split, recapitalization or similar event.

The Financing Warrants are exercisable, in whole orin part, but not in increments of less than $50,000 aggregate Exercise Price (unless the remaining aggregate Exercise Price is less than$50,000), beginning on May 4, 2023 and may be exercised at any time prior to their expiration. Holders of the Financing Warrants may exercisetheir Financing Warrants, at their election, by paying the Exercise Price in cash or, if at any time there is no effective registrationstatement registering, or no current prospectus available for, the resale of the underlying Common Shares, on a cashless exercise basis.On each of the first 12 monthly anniversaries of September 17, 2023, 1/12th of the Financing Warrants will expire.

The Financing Warrants have customary anti-dilutionadjustments to be determined in accordance with the requirements of the applicable stock exchanges.

The terms of the Financing Warrants restrict the exerciseof Financing Warrants by YA if such an exercise would cause YA to exceed certain beneficial ownership thresholds in NioCorp or such anexercise would cause the aggregate number of Common Shares issued pursuant to the Yorkville Convertible Debt Financing Agreement to exceedthe thresholds for issuance of Common Shares under the rules of Nasdaq, unless prior shareholder approval is obtained.

Notes

On April 12, 2024, the Company issued and sold tothe YA and Lind Global Fund II LP (“Lind”), in a private placement (the “April 2024 Private Placement”), $8.0million aggregate principal amount of unsecured notes (the “Notes”), pursuant to a Securities Purchase Agreement, dated April11, 2024 (the “Purchase Agreement”), between the Company and each of YA and Lind, as purchasers (in such capacity, the “Purchasers”).Pursuant to the terms of the Notes, subject to certain exceptions as described below, on the first day of each calendar month, beginningon June 1, 2024 (excluding August 2024) (a “Payment Date”), the Company will be required to repay a portion of the outstandingbalance of all of the Notes, on a pro-rata basis, in an amount equal to the sum of (i) $1.4 million of principal (or the outstanding principalif less than such amount) in the aggregate among all of the outstanding Notes, plus (ii) 8.0% of the principal amount being paid (the“Payment Premium”), and (iii) accrued and unpaid interest, if any, as of the Payment Date. The Company is required to makepayments on each Payment Date until the entire outstanding principal is repaid, but will not have an obligation to make a payment on aPayment Date if the Equity Conditions (as defined below) are satisfied.

Pursuant to the Purchase Agreement, the Purchasersadvanced an aggregate of $6.96 million to NioCorp in consideration of the issuance by NioCorp to the Purchasers of $8.0 million aggregateprincipal amount of Notes and Warrants (the “April 2024 Warrants”) to purchase up to 615,385 Common Shares (the “April2024 Warrant Shares”). Each April 2024 Warrant is exercisable for one Common Share for cash or, if at any time there is no effectiveregistration statement registering, or no current prospectus available for, the resale of the underlying Common Shares, on a cashlessbasis at the option of the holder, at a price per Common Share of $3.25 (the “April 2024 Exercise Price”), subject to adjustmentfor recapitalizations, stock splits, reverse stock splits or similar events, and expires April 12, 2027.

Subject to certain limitations, including those asdescribed below, contained within the Notes, holders of the Notes will be entitled to convert the principal amount of, accrued and unpaidinterest, if any, and any Payment Premium that has become due and payable on each Note, from time to time over their term, into a numberof Common Shares equal to the quotient of the amount being converted divided by the fixed conversion price of $2.75 per Common Share (the“Fixed Conversion Price”) up to a maximum of 3,141,817 Common Shares (together with the April 2024 Warrant Shares, the “UnderlyingShares”). The terms of the Notes restrict the conversion of the Notes by a holder if such a conversion or exercise would cause suchholder to exceed certain beneficial ownership thresholds in NioCorp.

The Notes are the unsecured obligations of NioCorpand will mature on December 31, 2024. The Notes will incur a simple interest rate obligation of 0.0% per annum (which will increase to18.0% per annum upon the occurrence of an event of default). The outstanding principal amount of, accrued and unpaid interest, if any,on, and the Payment Premium, if any, on the Notes must be paid by NioCorp in cash when the same becomes due and payable under the termsof the Notes at their stated maturity, upon their redemption or otherwise.

As mentioned above, NioCorp is required to make paymentson each Payment Date until the entire outstanding principal is repaid, but will not have an obligation to make a payment on a PaymentDate if the Equity Conditions are satisfied. The “Equity Conditions” means (i) on each of the five consecutive trading daysprior a Payment Date (the “Measuring Period”) a registration statement registering the resale by the Purchasers of the UnderlyingShares under the Securities Act (the “Underlying Shares Registration Statement”) is effective and available for the resaleby the Purchasers of all Underlying Shares, (ii) NioCorp has no knowledge of any fact that would cause the Underlying Shares RegistrationStatement not to be effective and available for the resale of the Underlying Shares, (iii) on each day during the Measuring Period, theCommon Shares are designated for quotation on Nasdaq, or on such other market or exchange on which the Common Shares are then listed ortraded to the extent such other market or exchange is the principal U.S. trading market for the Common Shares (the “Principal U.S.Market”), and have not been suspended from trading nor have delisting or suspension of trading been threatened or pending, (iv)during the Measuring Period, an event of default has not occurred, (v) on each trading day during the Measuring Period, the daily U.S.dollar volume-weighted average price for a Common Share on the Principal U.S. Market as reported by Bloomberg Financial Markets is greaterthan 120% of the Fixed Conversion Price, (vi) on each trading day during the Measuring Period the average daily volume traded exceeded$500,000, and (vii) there is no limitation on conversion under the terms of Notes. In addition, any Payment Date and the amount payableto the holder of a Note on any such Payment Date may be modified from time to time upon mutual written consent of NioCorp and such holder.

Pursuant to the terms of the Notes, to the extenta holder is a party to Yorkville Equity Facility Financing Agreement, for so long as any amount remains outstanding under such holder’sNote, the amount of cash received by the Company as payment from such holder in respect of an Advance (as defined in the Yorkville EquityFacility Financing Agreement) is subject to a right of offset, exercisable in such holder’s sole discretion, against an equal amountof principal, accrued and unpaid interest, if any, and other amounts that have become due and payable under the Note, not to exceed $1.512million in any calendar month.

The Notes may also be redeemed at NioCorp’soption at any time and from time to time over their term at a redemption price equal to the principal amount being redeemed, plus thePayment Premium, plus accrued and unpaid interest, if any, as of the redemption date.

The Notes contain events of default customary forinstruments of their type (with customary grace periods, as applicable) and provide that, upon the occurrence of an event of default arisingfrom certain events of bankruptcy or insolvency with respect to NioCorp, all outstanding Notes will become due and payable immediatelywithout further action or notice. If any other type of event of default occurs and is continuing, then any holder may declare all of itsNotes to be due and payable immediately.

Pursuant to a global guaranty agreement, dated asof April 11, 2024, among ECRC and 0896800 B.C. Ltd. (together with ECRC, the “Guarantors”), the Guarantors guaranteed thefull, prompt and unconditional payment when due (whether at maturity, by acceleration or otherwise), and the performance of all liabilities,agreements and other obligations of NioCorp to the Purchasers contained in the Notes and the Purchase Agreement, to the extent such liabilities,agreements and obligations are payable in cash.

April 2024 Warrants

On April 12, 2024, in connection with the closingof the April 2024 Private Placement, the Company issued to the Purchasers, in proportion to the aggregate principal amount of Notes issuedto each Purchaser, April 2024 Warrants to purchase the April 2024 Warrant Shares, which is equal to 25% of the aggregate principal amountof Notes issued to the Purchasers divided by the April 2024 Exercise Price, subject to any adjustment to give effect to any stock dividend,stock split or recapitalization.

The terms of the April 2024 Warrants restrict theexercise of the April 2024 Warrants by a holder if such an exercise would cause such holder to exceed certain beneficial ownership thresholdsin NioCorp.

The April 2024 Warrants will be exercisable, inwhole or in part, but not in increments of less than $50,000 aggregate April 2024 Exercise Price (unless the remaining aggregateApril 2024 Exercise Price is less than $50,000), at any time on or before April 12, 2027. Holders of the April 2024 Warrants mayexercise their April 2024 Warrants, at their election, by paying the April 2024 Exercise Price in cash or on a cashless exercisebasis, if at any time there is no effective registration statement or prospectus available for the resale of the underlying CommonShares or an event of default under the Notes has occurred and is continuing.

The April 2024 Warrants are subject to adjustmentfor any stock dividend or other distribution, stock split, reverse stock split or recapitalization

Description of Warrants

General

The following description,together with the additional information we may include in any applicable prospectus supplement, summarizes the material terms and provisionsof the Warrants that we may offer under this prospectus. While the terms we have summarized below will apply generally to any Warrantsthat we may offer under this prospectus, we will describe the particular terms of any series of Warrants in more detail in the applicableprospectus supplement. The terms of any Warrants offered under a prospectus supplement may differ from the terms described below.

We will file as exhibitsto the registration statement of which this prospectus is a part, or will incorporate by reference from another report that we file withthe SEC, the form of Warrant agreement or Warrant indenture, which may include a form of Warrant certificate, that describes the termsof the particular series of Warrants we are offering before the issuance of the related series of Warrants. The following summary of materialprovisions of the Warrants and the Warrant agreements and the Warrant indentures are subject to, and qualified in their entirety by referenceto, all the provisions of the Warrant agreement or Warrant indenture, and Warrant certificate, applicable to a particular series of Warrants.We urge you to read the applicable prospectus supplement related to the particular series of Warrants that we sell under this prospectus,as well as the complete Warrant agreements, Warrant indentures and Warrant certificates that contain the terms of the Warrants.

We will describe in theapplicable prospectus supplement the terms relating to Warrants being offered including:

Before exercising theirWarrants, holders of Warrants will not have any of the rights of holders of the Common Shares purchasable upon such exercise, includingthe right to receive dividends, if any, or payments upon our liquidation, dissolution or winding up of our affairs or to exercise votingrights, if any.

Exercise of Warrants

Unless we otherwise specifyin the applicable prospectus supplement, each Warrant will entitle the holder to purchase one Common Share at the exercise price thatwe describe in the applicable prospectus supplement. Unless we otherwise specify in the applicable prospectus supplement, holders of theWarrants may exercise the Warrants at any time up to the specified time on the expiration date that we set forth in the applicable prospectussupplement, and after the close of business on the expiration date, unexercised Warrants will become void.

Holders of the Warrantsmay exercise the Warrants by delivering the Warrant certificate representing the Warrants to be exercised together with specified information,and paying the required amount to the Warrant agent in immediately available funds, as provided in the applicable prospectus supplement.We intend to set forth in any Warrant agreement or Warrant indenture and in the applicable prospectus supplement the information thatthe holder of the Warrant will be required to deliver to the Warrant agent.

Upon receipt of the requiredpayment and any Warrant certificate or other form required for exercise properly completed and duly executed at the corporate trust officeof the Warrant agent or any other office indicated in the applicable prospectus supplement, we will issue and deliver the Common Sharespurchasable upon such exercise. If fewer than all of the Warrants represented by the Warrant or Warrant certificate are exercised, thenwe will issue a new Warrant or Warrant certificate for the remaining amount of Warrants. If we so indicate in the applicable prospectussupplement, holders of the Warrants may surrender securities as all or part of the exercise price for Warrants.

Description of Units

As specified in the applicableprospectus supplement, we may issue units consisting of one or more of the following: Common Shares, Warrants or any combination of suchsecurities. The applicable prospectus supplement will describe:

Plan of Distribution

Wemay sell the securities from time to time in one or more transactions:

We may distribute thesecurities from time to time in one or more transactions at:

We will describe the methodof distribution of each series of securities in the applicable prospectus supplement.

We may determine the priceor other terms of the securities offered under this prospectus by use of an electronic auction. We will describe how any auction willdetermine the price or any other terms, how potential investors may participate in the auction and the nature of the underwriters’obligations in the related supplement to this prospectus.

Underwriters, dealersor agents may receive compensation in the form of discounts, concessions or commissions from us or our purchasers as their agents in connectionwith the sale of the securities. These underwriters, dealers or agents may be considered to be underwriters under the Securities Act.As a result, discounts, commissions or profits on resale received by underwriters, dealers or agents may be treated as underwriting discountsand commissions. Each prospectus supplement will identify any underwriter, dealer or agent, and describe any compensation received bythem from us. We may grant underwriters who participate in the distribution of securities an option to purchase additional securitiesto cover over-allotments, if any, in connection with the distribution.

We may have agreementswith the underwriters, dealers and agents to indemnify them against specified civil liabilities, including liabilities under the SecuritiesAct. Underwriters, dealers and agents may engage in transactions with or perform services for us in the ordinary course of their businesses.

To the extent required,this prospectus may be amended and supplemented from time to time to describe a specific plan of distribution.

Agents

We may designate agentswho agree to use their reasonable efforts to solicit purchases of our securities for the period of their appointment or to sell our securitieson a continuing basis.

Underwriters

If we use underwritersfor a sale of securities, the underwriters will acquire the securities for their own account. The underwriters may resell the securitiesin one or more transactions, including negotiated transactions, at a fixed public offering price or at varying prices determined at thetime of sale. The obligations of the underwriters to purchase the securities will be subject to the conditions set forth in the applicableunderwriting agreement. The underwriters will be obligated to purchase all the securities of the series offered if they purchase anyof the securities of that series. We may change from time to time any initial public offering price and any discounts or concessionsthe underwriters allow or reallow or pay to dealers. We may use underwriters with whom we have a material relationship. We will describethe nature of any such relationship in any prospectus supplement naming any such underwriter.

Direct Sales

We may also sell securitiesdirectly to one or more purchasers without using underwriters or agents. Underwriters, dealers and agents that participate in the distributionof the securities may be underwriters as defined in the Securities Act, and any discounts or commissions they receive from us and anyprofit on their resale of the securities may be treated as underwriting discounts and commissions under the Securities Act. We will identifyin the applicable prospectus supplement any underwriters, dealers or agents and will describe their compensation.

Trading Markets andListing of Securities

Unless otherwise specifiedin the applicable prospectus supplement, each class or series of securities will be a new issue with no established trading market, otherthan our Common Shares, which are listed on The Nasdaq Global Market. We may elect to list any other class or series of securities onany exchange or market, but we are not obligated to do so. It is possible that one or more underwriters may make a market in a class orseries of securities, but the underwriters will not be obligated to do so and may discontinue any market making at any time without notice.We cannot give any assurance as to the liquidity of the trading market for any of the securities.

Stabilization Activities

Any underwriter may engagein over-allotment, stabilizing transactions, short covering transactions and penalty bids in accordance with Regulation M under the ExchangeAct. Over-allotment involves sales in excess of the offering size, which create a short position. Stabilizing transactions permit bidsto purchase the underlying security so long as the stabilizing bids do not exceed a specified maximum. Short covering transactions involvepurchases of the securities in the open market after the distribution is completed to cover short positions. Penalty bids permit the underwritersto reclaim a selling concession from a dealer when the securities originally sold by the dealer are purchased in a covering transactionto cover short positions. Those activities may cause the price of the securities to be higher than it would otherwise be. If commenced,the underwriters may discontinue any of these activities at any time.

Delayed Delivery Contracts

If we so indicate in theprospectus supplement, we may authorize agents, underwriters or dealers to solicit offers from certain types of institutions to purchasesecurities from us at the public offering price under delayed delivery contracts. These contracts would provide for payment and deliveryon a specified date in the future. The contracts would be subject only to those conditions described in the prospectus supplement. Theprospectus supplement will describe the commission payable for solicitation of those contracts.

Legal Matters

The validity of the securitiesin respect of which this prospectus is being delivered will be passed upon for us by Blake, Cassels & Graydon LLP, Vancouver, BritishColumbia, Canada, relating to matters of British Columbia or Canadian law, and Jones Day, relating to matters of New York or U.S. federallaw. Additional legal matters may be passed upon for us or any underwriters, dealers or agents by counsel that we will name in the applicableprospectus supplement.

Experts

The consolidated financial statements of NioCorp DevelopmentsLtd. as of June 30, 2023 and 2022 and for each of the three years in the period ended June 30, 2023, incorporated by reference in thisprospectus and in the registration statement have been so incorporated in reliance on the report of BDO USA, P.C., an independent registeredpublic accounting firm, given on the authority of said firm as experts in auditing and accounting. The report on the consolidated financialstatements contains an explanatory paragraph regarding NioCorp Developments Ltd.’s ability to continue as a going concern.

The financial statements of GX Acquisition Corp. IIas of December 31, 2022 and 2021 and for the years ended December 31, 2022 and 2021, have been audited by Marcum LLP, an independent registeredpublic accounting firm, as set forth in their report (which contains an explanatory paragraph relating to substantial doubt about theability of GX Acquisition Corp. II to continue as a going concern as described in Note 1 to GXII’s financial statements), and areincorporated by reference in this prospectus and in the registration statement of which this prospectus is a part have been so incorporatedin reliance on such report given upon such firm as experts in auditing and accounting.

The technical report summary for the Elk CreekProject prepared in accordance with subpart 1300 of Regulation S-K (the “S-K 1300 Elk Creek Technical Report Summary”), whichis incorporated by reference in this prospectus, and the information summarized or quoted from the S-K 1300 Elk Creek Technical ReportSummary included or incorporated by reference in this prospectus have been so included or incorporated by reference with the consent ofthe following qualified persons, as such term is defined in Item 1300 of Regulation S-K, who prepared the S-K 1300 Elk Creek TechnicalReport Summary and reviewed and approved such information summarized or quoted therefrom included or incorporated by reference in thisprospectus: Dahrouge Geological Consulting USA Ltd.; Understood Mineral Resources Ltd.; Optimize Group; Tetra Tech; Adrian Brown ConsultantsInc.; Metallurgy Concept Solutions; Magemi Mining Inc.; L3 Process Development; Olsson; A2GC; Scott Honan, M.Sc, SME-RM, NioCorp; Cementation;Mahmood Khwaja, P.E., CDM Smith; and Wynand Marx, M.Eng, BBE Consulting. A matrix of the sections of the S-K 1300 Elk Creek TechnicalReport Summary for which each qualified person is responsible is included in the S-K 1300 Elk Creek Technical Report Summary. Except forScott Honan, none of the qualified persons is affiliated with NioCorp. Mr. Honan is the Chief Operating Officer of NioCorp.

PART II

INFORMATION NOT REQUIRED IN PROSPECTUS

The following table sets forth the fees and expensespayable by us in connection with the sale and distribution of the securities being registered hereby. All amounts are estimates, exceptfor the Securities and Exchange Commission (“SEC”) registration fee:

* These fees and expenses are calculated based on the securities offeredand the number of issuances and, accordingly, cannot be estimated at this time.

The corporate laws of British Columbia allow NioCorpDevelopments Ltd. (“we,” “us,” “our,” “NioCorp” or the “Company”), and itscorporate articles require it (subject to the provisions of the British Columbia Business Corporations Act (“BCBCA”) notedbelow and the undertakings provided in Item 17 below), to indemnify its directors, former directors, alternate directors and their heirsand legal personal representatives against all eligible penalties to which such person is or may be liable, and NioCorp must, after thefinal disposition of an eligible proceeding, pay the expenses actually and reasonably incurred by such person in respect of that proceeding.Each director and alternate director is deemed to have contracted with NioCorp on the terms of the indemnity contained in NioCorp’sarticles.

For the purposes of such an indemnification:

In addition, under the BCBCA, NioCorp may pay, asthey are incurred in advance of the final disposition of an eligible proceeding, the expenses actually and reasonably incurred by an eligibleparty in respect of that proceeding, provided that NioCorp first receives from the eligible party a written undertaking that, if it isultimately determined that the payment of expenses is prohibited by the restrictions noted below, the eligible party will repay the amountsadvanced.

Notwithstanding the provisions of NioCorp’sarticles noted above, NioCorp must not indemnify an eligible party or pay the expenses of an eligible party, if any of the following circ*mstancesapply:

In addition, if an eligible proceeding is broughtagainst an eligible party by or on behalf of NioCorp or by or on behalf of an associated corporation, NioCorp must not do either of thefollowing:

Notwithstanding any of the foregoing, and whetheror not payment of expenses or indemnification has been sought, authorized or declined under the BCBCA or the articles of NioCorp, on theapplication of NioCorp or an eligible party, the Supreme Court of British Columbia may do one or more of the following:

Furthermore, we have entered into an indemnificationagreement with each of our directors and executive officers. The indemnification agreements provide that NioCorp will, to the fullestextent possible under applicable law, subject to other specified limitations, indemnify and hold harmless the directors and executiveofficers against any and all costs and expenses reasonably incurred for, or in connection with, any civil, criminal, administrative, investigativeor other proceeding, whether threatened, pending, continuing or completed, including but not limited to any act, matter, deed or thingwhatsoever made, done, committed, permitted or acquiesced in.

INDEX TO EXHIBITS

The undersigned registranthereby undertakes:

provided, however,that paragraphs (i), (ii) and (iii) above do not apply if the information required to be included in a post-effective amendment by thoseparagraphs is contained in reports filed with or furnished to the Securities and Exchange Commission by the registrant pursuant to Section13 or Section 15(d) of the Securities Exchange Act of 1934 that are incorporated by reference in the registration statement, or is containedin a form of prospectus filed pursuant to Rule 424(b) that is part of the registration statement.

SIGNATURES

Pursuant to the requirementsof the Securities Act of 1933, the registrant certifies that it has reasonable grounds to believe that it meets all of the requirementsfor filing on Form S-3 and has duly caused this Registration Statement on Form S-3 to be signed on its behalf by the undersigned, thereuntoduly authorized, in the City of Centennial, State of Colorado, on June 13, 2024.

Pursuant to the requirementsof the Securities Act of 1933, as amended, this Registration Statement has been signed by the following persons in the capacities andon the dates indicated.

KNOW ALL PERSONS BY THESEPRESENTS, that each of the directors and officers of the registrant whose signature appears below constitutes and appoints Mark A. Smithand Neal Shah, or either of them, as true and lawful attorneys-in-fact and agents with full power of substitution and re-substitution,for him and in his name, place and stead, in any and all capacities to sign the Registration Statement filed herewith and any or all amendmentsto said Registration Statement (including post-effective amendments and Registration Statements filed pursuant to Rule 462 and otherwise),and to file the same, with all exhibits thereto, and other documents in connection therewith, the Securities and Exchange Commission grantingunto said attorney-in-fact and agents the full power and authority to do and perform each and every act and thing requisite and necessaryto be done in and about the foregoing, as to all intents and purposes as he might or could do in person, hereby ratifying and confirmingall that said attorney-in-fact and agents or any of them, or his substitute, may lawfully do or cause to be done by virtue hereof.

RE: NioCorp Developments Ltd. – Registration Statement on FormS-3

Dear Sirs and Mesdames:

We have acted as Canadian counsel to NioCorp DevelopmentsLtd., a corporation incorporated under the laws of the Province of British Columbia (the “Company”), in connectionwith the preparation and filing by the Company with the United States Securities and Exchange Commission (the “SEC”)on the date hereof of the above captioned registration statement on Form S-3 (the “Registration Statement”) under theUnited States Securities Act of 1933, as amended (the “Act”). The Registration Statement registers the issuance andsale of up to US$200,000,000 of the Company’s common shares (the “Shares”), warrants to purchase Shares (the“Warrants”) and units comprised of one or more of the securities described herein, in any combination (the “Units”and, together with the Shares and the Warrants, the “Securities”), all of which may be issued from time to time ona delayed or continuous basis pursuant to Rule 415 under the Act.

The Registration Statement includes a prospectus (the“Prospectus”), which provides that it will be supplemented in the future by one or more prospectus supplements.

In connection with the opinions hereinafter set forth,we have considered such matters of fact and questions of law and examined such documents, records and certificates as we have consideredappropriate for purposes of this opinion letter, including, without limitation, the following:

We are solicitors qualified to carry on the practiceof law in the Province of British Columbia. Our opinions hereinafter set forth are expressed only with respect to the laws of the Provinceof British Columbia and the federal laws of Canada applicable therein, in each case, in effect on the date hereof. We express no opinionwith respect to the laws of any other jurisdiction.

We have no responsibility or obligation to (i) updatethis opinion, (ii) take into account or inform the addressee or any other person of any changes in law, facts or other developments subsequentto the date hereof that do or may affect the opinions we express herein or (iii) advise the addressee or any other person of any otherchange in any matter addressed in this opinion. Nor do we have any responsibility or obligation to consider the applicability or correctnessof this opinion to any person other than the addressee.

We have also assumed without independentinvestigation that: (i) all information contained in all documents reviewed by us is true and correct, (ii) the genuineness of all signatureson all documents reviewed by us, (iii) the authenticity and completeness of all documents submitted to us as originals, (iv) the conformityto authentic originals of all documents submitted to us as certified or photostatic copies, (v) each natural person signing any documentreviewed by us had the legal capacity to do so, none of which facts we have independently verified, (vi) no order, ruling or decisionof any court or regulatory or administrative body is in effect at any relevant time that restricts the issuance of the Securities, (vii)there is no foreign law that would affect the opinions expressed herein and (viii) at the time of the execution and delivery of any documentsrelating to the Securities or the offering thereof, to the extent such documents purport to constitute agreements, such documents constitutevalid and binding obligations of such parties. We also have assumed the due authorization, execution and delivery of all documents whereauthorization, execution and delivery are prerequisites to the effectiveness of such documents.

We have also assumed that at all relevant times:

In giving the opinion in paragraph 1, we have reliedsolely upon the Certificate of Good Standing.

Based upon the foregoing, and subject to the qualifications,assumptions and limitations stated herein, we are of the opinion that:

This opinion letter has been prepared for your usein connection with the Registration Statement and is expressed as of the date hereof. The opinions expressed herein are limited to thematters set forth above and we render no opinion, whether by implication or otherwise, as to any other matters relating to the Company,the Prospectus, the Registration Statement or the Securities.

* * * * *

We hereby consent to the filing of this opinion letteras an exhibit to the Registration Statement and to the reference to Blake, Cassels & Graydon LLP under the caption “LegalMatters” in the Prospectus. In giving this consent, we do not hereby agree that we are within the category of persons whoseconsent is required under Section 7 of the Act or the rules and regulations of the SEC promulgated thereunder.

Yours very truly,

/s/ Blake, Cassels & Graydon LLP

Exhibit 5.2

NorthPoint • 901 Lakeside Avenue • Cleveland, Ohio 44114.1190

Telephone:+1.216.586.3939 • jonesday.com

NioCorp Developments Ltd.
7000 South Yosemite Street, Suite 115
Centennial, Colorado 80112

Ladies and Gentlemen:

We have acted as counsel for NioCorp DevelopmentsLtd., a corporation incorporated under the laws of the Province of British Columbia (the “Company”), in connectionwith the authorization of the possible issuance and sale from time to time, on a delayed basis, by the Company of up to $200,000,000 aggregateinitial offering amount of: (i) common shares, without par value, of the Company (the “Common Shares”); (ii)warrants to purchase Common Shares (the “Warrants”); and (iii) units consisting of one or more of the securitiesdescribed in clauses (i) and (ii) above (the “Units” and, together with the Common Shares and the Warrants,the “Securities”), as contemplated by the Registration Statement on Form S-3 to which this opinion is filedas an exhibit (as the same may be amended from time to time, the “Registration Statement”). The Securities maybe offered and sold from time to time pursuant to Rule 415 under the Securities Act of 1933 (the “Securities Act”).

In connection with the opinions expressed herein,we have examined such documents, records and matters of law as we have deemed relevant or necessary for purposes of such opinions. Basedon the foregoing, and subject to the further limitations, qualifications and assumptions set forth herein, we are of the opinion that:

In rendering the foregoing opinions, wehave assumed that: (i) the Company is a corporation existing and in good standing under the laws of the Province of BritishColumbia; (ii) the Registration Statement, and any amendments thereto, will have become effective (and will remain effective at thetime of issuance of any Securities thereunder); (iii) a prospectus supplement describing each class or series of Securities offeredpursuant to the Registration Statement, to the extent required by applicable law and relevant rules and regulations of theSecurities and Exchange Commission (the “Commission”), will be timely filed with the Commission; (iv) thedefinitive terms of each class and/or series of Securities will have been established in accordance with the authorizing resolutionsadopted by the Company’s Board of Directors (or an authorized committee or subcommittee thereof), the Company’s noticeof articles (the “Notice of Articles”) and articles (the “Articles”), andapplicable law; (v) the Company will issue and deliver the Securities in the manner contemplated by the Registration Statement; (vi)the resolutions authorizing the Company to issue, offer and sell the Securities will have been adopted by the Company’s Boardof Directors (or an authorized committee or subcommittee thereof) and will be in full force and effect at all times at which theSecurities are offered or sold by the Company and the Company will take no action inconsistent with such resolutions; (vii) allSecurities will be issued in compliance with applicable federal and state securities laws; (viii) any Warrant Agreement (as definedbelow), Warrants and Unit Agreement (as defined below) will be governed by and construed in accordance with the laws of the State ofNew York and will constitute a valid and binding obligation of each party thereto other than the Company; and (ix) the choice of NewYork law to govern any Warrant Agreement, Warrants and Unit Agreement and the choice of New York forum provisions of any WarrantAgreement, Warrants and Unit Agreement will be valid choices under the laws of Canada (including the laws of the provincesthereof).

With respect to any Securities consisting ofWarrants, we have further assumed that: (i) the warrant agreement, approved by us, relating to the Warrants (the “WarrantAgreement”) to be entered into between the Company and an entity selected by the Company to act as the warrant agent (the“Warrant Agent”) will have been authorized, executed and delivered by the Warrant Agent; and (ii) the Warrantswill have been authorized, executed and delivered by the Warrant Agent in accordance with the provisions of the Warrant Agreement.

With respect to any Securities consisting ofUnits, we have further assumed that: (i) the applicable unit agreement, if any (the “Unit Agreement”), and eachcomponent of any Unit will be authorized, executed and delivered by any third party (to the extent applicable) as contemplated by theRegistration Statement and the Unit Agreement; and (ii) each component of any Unit will constitute a valid and binding obligation of anythird party (to the extent applicable) as contemplated by the Registration Statement and the Unit Agreement.

We have further assumed that: (i) any WarrantAgreement, Warrants and Unit Agreement will have been authorized by all necessary corporate action of the Company and executed and deliveredby the Company under the laws of Canada (including the laws of the provinces thereof); (ii) each component of any Unit will have beenauthorized by all necessary corporate action of the Company and executed and delivered by the Company (to the extent applicable) underthe laws of Canada (including the laws of the provinces thereof) and in accordance with the provisions of the Unit Agreement; and (iii)the execution, delivery, performance and compliance with the terms and provisions of any Warrant Agreement, Warrants and Unit Agreementby the Company do not violate or conflict with the laws of Canada (including the laws of the provinces thereof) or the terms and conditionsof the Notice of Articles or Articles.

Further, it is understood that we express noopinion with respect to any matters relating to the Common Shares that are governed by the laws of Canada (including the laws of the provincesthereof), including, without limitation, the authorization, issuance or delivery of any Common Shares that may be issuable upon exerciseof the Warrants or that may be a component of any Unit. In this regard, (x) we have further assumed that (1) the resolutions of the Boardof Directors of the Company authorizing the issuance or sale of the Common Shares that may be issuable upon exercise of the Warrants onthe terms and subject to the conditions set forth in the Warrant Agreement and the Warrants or as a component of the Units on the termsand subject to the conditions set forth in the Unit Agreement will be in full force and effect at all times at which any such Common Sharesare issued or sold by the Company and (2) the Company will take no action inconsistent with such resolutions, including, without limitation,by causing more Common Shares to be issued than then remain authorized but unissued under the Warrants and the Units and (y) we expressno opinion to the extent that adjustments to the Warrants or the exercise price thereunder may cause the Warrants to be exercisable formore Common Shares than then remain authorized but unissued.

The opinions expressed herein are limited bybankruptcy, insolvency, reorganization, fraudulent transfer and fraudulent conveyance, voidable preference, moratorium or other similarlaws and related regulations and judicial doctrines from time to time in effect relating to or affecting creditors’ rights generally,and by general equitable principles and public policy considerations, whether such principles and considerations are considered in a proceedingat law or at equity.

As to facts material to the opinions and assumptionsexpressed herein, we have relied upon oral or written statements and representations of officers and other representatives of the Companyand others. The opinions expressed herein are limited to the laws of the State of New York, as currently in effect, and we express noopinion as to the effect of the laws of any other jurisdiction.

We hereby consent to the filing of this opinionas Exhibit 5.2 to the Registration Statement and to the reference to Jones Day under the caption “Legal Matters” in the prospectusconstituting a part of such Registration Statement. In giving such consent, we do not thereby admit that we are included in the categoryof persons whose consent is required under Section 7 of the Securities Act or the rules and regulations of the Commission promulgatedthereunder.

Very truly yours,

/s/ Jones Day

Exhibit 23.3

Consent of Independent Registered Public AccountingFirm

We hereby consent to the incorporation by reference in the Prospectus constitutinga part of this Registration Statement of our report dated October 6, 2023, relating to the consolidated financial statements of NioCorpDevelopments Ltd. (the Company) appearing in the Company’s Annual Report on Form 10-K for the year ended June 30, 2023. Our reportcontains an explanatory paragraph regarding the Company’s ability to continue as a going concern.

We also consent to the reference to us under the caption“Experts” in the Prospectus.

/s/ BDO USA, P.C.

Spokane, Washington

June 13, 2024

Exhibit 23.4

IndependentRegistered Public Accounting Firm’s Consent

We consent to the incorporation by reference in thisRegistration Statement of NioCorp Developments Ltd. on Form S-3 of our report dated February 23, 2023, which includes an explanatory paragraphas to GX Acquisition Corp. II’s ability to continue as a going concern with respect to our audits of the financial statements ofGX Acquisition Corp. II as of December 31, 2022 and 2021 and for the years ended December 31, 2022 and 2021 appearing in the Current Reporton Form 8-K of NioCorp Developments Ltd. filed with the Securities and Exchange Commission on March 1, 2023. We were dismissed as auditorson March 17, 2023, and accordingly, we have not performed any audit or review procedures with respect to any financial statements appearingin such Prospectus for the periods after the date of our dismissal.

We also consent to the reference to our firm underthe heading “Experts” in the Prospectus, which is part of this Registration Statement.

/s/ Marcum LLP

Marcum llp

New York, NY

June 13, 2024

Exhibit 23.5

CONSENTOF QUALIFIED PERSON

DahrougeGeological Consulting USA Ltd. hereby consents to the public filing of Sections 1.1 to 1.5, 1.9 to 1.11, 2 to 6, 7.1 to 7.2, 8, 9.2,9.3, 16, 18 to 21, 22.1, 22.3, 22.9 to 22.12, 23.1.1, and 23.1.9 (the “Covered Sections”) of the Technical Report Summarytitled “Technical Report Summary, Elk Creek Project, Nebraska” with an Effective Date of June 30, 2022 (the “TechnicalReport Summary”) as an exhibit to this Registration Statement on Form S-3 and any and all amendments and supplements thereto (the“Registration Statement”) of NioCorp Developments Ltd. (the “Company”).

DahrougeGeological Consulting USA Ltd. also consents to the use of and references to our name, including our status as an expert or “qualifiedperson” (as defined in Subpart 1300 of Regulation S-K promulgated by the U.S. Securities and Exchange Commission), in connectionwith the Registration Statement and the Technical Report Summary.

DahrougeGeological Consulting USA Ltd. also consents to any extracts from or a summary of the Covered Sections in the Registration Statement(the “Disclosure”).

DahrougeGeological Consulting USA Ltd. certifies that we have read the Disclosure being filed by the Company and that it fairly and accuratelyrepresents the information in the Covered Sections.

Signedand dated this 13^th dayof June 2024 at Centennial, Colorado.

Exhibit 23.6

CONSENTOF QUALIFIED PERSON

Understood MineralResources Ltd. hereby consents to the public filing of Sections 1.6, 9.1, 11 and 22.2 (the “Covered Sections”) of the TechnicalReport Summary titled “Technical Report Summary, Elk Creek Project, Nebraska” with an Effective Date of June 30, 2022 (the“Technical Report Summary”) as an exhibit to this Registration Statement on Form S-3 and any and all amendments and supplementsthereto (the “Registration Statement”) of NioCorp Developments Ltd. (the “Company”).

Understood MineralResources Ltd. also consents to the use of and references to our name, including our status as an expert or “qualified person”(as defined in Subpart 1300 of Regulation S-K promulgated by the U.S. Securities and Exchange Commission), in connection with the RegistrationStatement and the Technical Report Summary.

Understood MineralResources Ltd. also consents to any extracts from or a summary of the Covered Sections in the Registration Statement (the “Disclosure”).

Understood MineralResources Ltd. certifies that we have read the Disclosure being filed by the Company and that it fairly and accurately represents theinformation in the Covered Sections.

Signedand dated this 13^th day of June 2024 at 22 MiddletonCrescent, Saskatoon, Saskatchewan, Canada.

Exhibit 23.7

CONSENTOF QUALIFIED PERSON

Optimize Group Inc.hereby consents to the public filing of Sections 1.7, 12, 13.3 to 13.5, 15.7, 22.5 and 23.1.4 (the “Covered Sections”) ofthe Technical Report Summary titled “Technical Report Summary, Elk Creek Project, Nebraska” with an Effective Date of June30, 2022 (the “Technical Report Summary”) as an exhibit to this Registration Statement on Form S-3 and any and all amendmentsand supplements thereto (the “Registration Statement”) of NioCorp Developments Ltd. (the “Company”).

Optimize Group Inc.also consents to the use of and references to our name, including our status as an expert or “qualified person” (as definedin Subpart 1300 of Regulation S-K promulgated by the U.S. Securities and Exchange Commission), in connection with the Registration Statementand the Technical Report Summary.

Optimize Group Inc.also consents to any extracts from or a summary of the Covered Sections in the Registration Statement (the “Disclosure”).

Optimize Group Inc.certifies that we have read the Disclosure being filed by the Company and that it fairly and accurately represents the information inthe Covered Sections.

Signed and dated this13^th day of June 2024 at Toronto, Ontario, Canada.

Exhibit 23.8

CONSENTOF QUALIFIED PERSON

Tetra Tech herebyconsents to the public filing of Sections 14.5, 15.1.1, 15.1.2, 15.2 to 15.4, 22.7 and 23.1.6 (the “Covered Sections”) ofthe Technical Report Summary titled “Technical Report Summary, Elk Creek Project, Nebraska” with an Effective Date of June30, 2022 (the “Technical Report Summary”) as an exhibit to this Registration Statement on Form S-3 and any and all amendmentsand supplements thereto (the “Registration Statement”) of NioCorp Developments Ltd. (the “Company”).

Tetra Tech also consentsto the use of and references to our name, including our status as an expert or “qualified person” (as defined in Subpart1300 of Regulation S-K promulgated by the U.S. Securities and Exchange Commission), in connection with the Registration Statement andthe Technical Report Summary.

Tetra Tech also consentsto any extracts from or a summary of the Covered Sections in the Registration Statement (the “Disclosure”).

Tetra Tech certifiesthat we have read the Disclosure being filed by the Company and that it fairly and accurately represents the information in the CoveredSections.

Signed and dated this13^th day of June 2024 at Salt Lake City, Utah.

Exhibit 23.9

CONSENTOF QUALIFIED PERSON 

Adrian Brown ConsultantsInc. hereby consents to the public filing of Sections 7.4.1, 7.4.2 and 13.2 (the “Covered Sections”) of the Technical ReportSummary titled “Technical Report Summary, Elk Creek Project, Nebraska” with an Effective Date of June 30, 2022 (the “TechnicalReport Summary”) as an exhibit to this Registration Statement on Form S-3 and any and all amendments and supplements thereto (the“Registration Statement”) of NioCorp Developments Ltd. (the “Company”).

Adrian Brown ConsultantsInc. also consents to the use of and references to our name, including our status as an expert or “qualified person” (asdefined in Subpart 1300 of Regulation S-K promulgated by the U.S. Securities and Exchange Commission), in connection with the RegistrationStatement and the Technical Report Summary.

Adrian Brown ConsultantsInc. also consents to any extracts from or a summary of the Covered Sections in the Registration Statement (the “Disclosure”).

Adrian Brown ConsultantsInc. certifies that we have read the Disclosure being filed by the Company and that it fairly and accurately represents the informationin the Covered Sections.

Signed and dated this13^th day of June 2024 at Denver, Colorado, USA.

Exhibit 23.10

CONSENTOF QUALIFIED PERSON

Magemi Mining Inc.hereby consents to the public filing of Sections 10.1, 14.1.1, 14.2.1, 14.3.1, and 14.4.1 (the “Covered Sections”) of theTechnical Report Summary titled “Technical Report Summary, Elk Creek Project, Nebraska” with an Effective Date of June 30,2022 (the “Technical Report Summary”) as an exhibit to this Registration Statement on Form S-3 and any and all amendmentsand supplements thereto (the “Registration Statement”) of NioCorp Developments Ltd. (the “Company”).

Magemi Mining Inc.also consents to the use of and references to our name, including our status as an expert or “qualified person” (as definedin Subpart 1300 of Regulation S-K promulgated by the U.S. Securities and Exchange Commission), in connection with the Registration Statementand the Technical Report Summary.

Magemi Mining Inc.also consents to any extracts from or a summary of the Covered Sections in the Registration Statement (the “Disclosure”).

Magemi Mining Inc.certifies that we have read the Disclosure being filed by the Company and that it fairly and accurately represents the information inthe Covered Sections.

Signedand dated this 13^th day of June 2024 at North York,Ontario, Canada.

Exhibit 23.11

CONSENTOF QUALIFIED PERSON

L3 Process Developmenthereby consents to the public filing of Sections 10.2, 10.2.1 to 10.2.3, 14.1.2, 14.1.4, 14.2.2, 14.2.4, 14.3.2, 14.3.4, 14.4.2, 14.4.4,22.4, 22.6, 23.1.2, and 23.1.5 (the “Covered Sections”) of the Technical Report Summary titled “Technical Report Summary,Elk Creek Project, Nebraska” with an Effective Date of June 30, 2022 (the “Technical Report Summary”) as an exhibitto this Registration Statement on Form S-3 and any and all amendments and supplements thereto (the “Registration Statement”)of NioCorp Developments Ltd. (the “Company”).

L3 Process Developmentalso consents to the use of and references to our name, including our status as an expert or “qualified person” (as definedin Subpart 1300 of Regulation S-K promulgated by the U.S. Securities and Exchange Commission), in connection with the Registration Statementand the Technical Report Summary.

L3 Process Developmentalso consents to any extracts from or a summary of the Covered Sections in the Registration Statement (the “Disclosure”).

L3 Process Developmentcertifies that we have read the Disclosure being filed by the Company and that it fairly and accurately represents the information inthe Covered Sections.

Signed and dated this13^th day of June 2024 at Salt Lake City.

Exhibit 23.12

CONSENTOF QUALIFIED PERSON

Olsson hereby consentsto the public filing of Sections 1.8, 17, 22.8 and 23.1.7 (the “Covered Sections”) of the Technical Report Summary titled“Technical Report Summary, Elk Creek Project, Nebraska” with an Effective Date of June 30, 2022 (the “Technical ReportSummary”) as an exhibit to this Registration Statement on Form S-3 and any and all amendments and supplements thereto (the “RegistrationStatement”) of NioCorp Developments Ltd. (the “Company”).

Olsson also consents tothe use of and references to our name, including our status as an expert or “qualified person” (as defined in Subpart 1300of Regulation S-K promulgated by the U.S. Securities and Exchange Commission), in connection with the Registration Statement and theTechnical Report Summary.

Olsson also consents toany extracts from or a summary of the Covered Sections in the Registration Statement (the “Disclosure”).

Olsson certifies thatwe have read the Disclosure being filed by the Company and that it fairly and accurately represents the information in the Covered Sections.

Signed and dated this 13^thday of June 2024 at Omaha, Nebraska.

Exhibit 23.13

CONSENTOF QUALIFIED PERSON

A2GC hereby consentsto the public filing of Sections 7.3, 13.1 and 23.1.3 (the “Covered Sections”) of the Technical Report Summary titled “TechnicalReport Summary, Elk Creek Project, Nebraska” with an Effective Date of June 30, 2022 (the “Technical Report Summary”)as an exhibit to this Registration Statement on Form S-3 and any and all amendments and supplements thereto (the “RegistrationStatement”) of NioCorp Developments Ltd. (the “Company”).

A2GC also consentsto the use of and references to our name, including our status as an expert or “qualified person” (as defined in Subpart1300 of Regulation S-K promulgated by the U.S. Securities and Exchange Commission), in connection with the Registration Statement andthe Technical Report Summary.

A2GC also consentsto any extracts from or a summary of the Covered Sections in the Registration Statement (the “Disclosure”).

A2GC certifies thatwe have read the Disclosure being filed by the Company and that it fairly and accurately represents the information in the Covered Sections.

Signed and dated this13^th day of June 2024 in Montreal, Quebec, Canada.

Exhibit 23.14

CONSENTOF QUALIFIED PERSON

Metallurgy Concept SolutionsLLC hereby consents to the public filing of Sections 10.3, 14.1.3, 14.2.3, 14.3.3, and 14.4.3 (the “Covered Sections”) ofthe Technical Report Summary titled “Technical Report Summary, Elk Creek Project, Nebraska” with an Effective Date of June30, 2022 (the “Technical Report Summary”) as an exhibit to this Registration Statement on Form S-3 and any and all amendmentsand supplements thereto (the “Registration Statement”) of NioCorp Developments Ltd. (the “Company”).

Metallurgy Concept SolutionsLLC also consents to the use of and references to our name, including our status as an expert or “qualified person” (as definedin Subpart 1300 of Regulation S-K promulgated by the U.S. Securities and Exchange Commission), in connection with the Registration Statementand the Technical Report Summary.

Metallurgy Concept SolutionsLLC also consents to any extracts from or a summary of the Covered Sections in the Registration Statement (the “Disclosure”).

Metallurgy Concept SolutionsLLC certifies that we have read the Disclosure being filed by the Company and that it fairly and accurately represents the informationin the Covered Sections.

Signed and dated this 13^thday of June 2024 at 306 S. Main Street., Union, Oregon, United States 97883.

Exhibit 23.15 

CONSENTOF QUALIFIED PERSON

I, Scott Honan, M.Sc.,SME-RM, consent to the public filing of Sections 13.7.5, 13.7.6, 13.7.7, 13.7.8, 13.7.15, 15.5, 15.6 and 22.7.1 (the “Covered Sections”)of the Technical Report Summary titled “Technical Report Summary, Elk Creek Project, Nebraska” with an Effective Date ofJune 30, 2022 (the “Technical Report Summary”) as an exhibit to this Registration Statement on Form S-3 and any and all amendmentsand supplements thereto (the “Registration Statement”) of NioCorp Developments Ltd. (the “Company”).

I also consent to theuse of and references to my name, including my status as an expert or “qualified person” (as defined in Subpart 1300 of RegulationS-K promulgated by the U.S. Securities and Exchange Commission), in connection with the Registration Statement and the Technical ReportSummary.

I also consent to anyextracts from or a summary of the Covered Sections in the Registration Statement (the “Disclosure”).

I certify that I haveread the Disclosure being filed by the Company and that it fairly and accurately represents the information in the Covered Sections.

Signed and dated this 13^thday of June 2024 at Centennial, Colorado, USA.

Exhibit 23.16 

CONSENTOF QUALIFIED PERSON

Cementation hereby consentsto the public filing of Sections 13.7.1, 13.7.2, 13.7.3, 13.7.4, 13.7.12, 13.7.9, 13.7.10, 13.7.11, 13.7.13, 13.7.14, 15.1.3, 15.1.4and 23.1.8 (the “Covered Sections”) of the Technical Report Summary titled “Technical Report Summary, Elk Creek Project,Nebraska” with an Effective Date of June 30, 2022 (the “Technical Report Summary”) as an exhibit to this RegistrationStatement on Form S-3 and any and all amendments and supplements thereto (the “Registration Statement”) of NioCorp DevelopmentsLtd. (the “Company”).

Cementation also consentsto the use of and references to our name, including our status as an expert or “qualified person” (as defined in Subpart1300 of Regulation S-K promulgated by the U.S. Securities and Exchange Commission), in connection with the Registration Statement andthe Technical Report Summary.

Cementation also consentsto any extracts from or a summary of the Covered Sections in the Registration Statement (the “Disclosure”).

Cementation certifiesthat we have read the Disclosure being filed by the Company and that it fairly and accurately represents the information in the CoveredSections.

Signed and dated this 13^thday of June 2024 at Salt Lake City, Utah.

Exhibit 23.17

CONSENTOF QUALIFIED PERSON

I, Mahmood Khwaja, P.E., consentto the public filing of Section 15.8 (the “Covered Section”) of the Technical Report Summary titled “Technical ReportSummary, Elk Creek Project, Nebraska” with an Effective Date of June 30, 2022 (the “Technical Report Summary”) as anexhibit to this Registration Statement on Form S-3 and any and all amendments and supplements thereto (the “Registration Statement”)of NioCorp Developments Ltd. (the “Company”).

I also consent to the use of andreferences to my name, including my status as an expert or “qualified person” (as defined in Subpart 1300 of Regulation S-Kpromulgated by the U.S. Securities and Exchange Commission), in connection with the Registration Statement and the Technical Report Summary.

I also consent to any extractsfrom or a summary of the Covered Section in the Registration Statement (the “Disclosure”).

I certify that I have read theDisclosure being filed by the Company and that it fairly and accurately represents the information in the Covered Section.

Signed and dated this 13^thday of June 2024 at Boston, Massachusetts, USA.

Exhibit 23.18 

CONSENTOF QUALIFIED PERSON

I, Wynand Marx, M.Eng., consentto the public filing of Section 13.6 (the “Covered Section”) of the Technical Report Summary titled “Technical ReportSummary, Elk Creek Project, Nebraska” with an Effective Date of June 30, 2022 (the “Technical Report Summary”) as anexhibit to this Registration Statement on Form S-3 and any and all amendments and supplements thereto (the “Registration Statement”)of NioCorp Developments Ltd. (the “Company”).

I also consent to the use of andreferences to my name, including my status as an expert or “qualified person” (as defined in Subpart 1300 of Regulation S-Kpromulgated by the U.S. Securities and Exchange Commission), in connection with the Registration Statement and the Technical Report Summary.

I also consent to any extractsfrom or a summary of the Covered Section in the Registration Statement (the “Disclosure”).

I certify that I have read theDisclosure being filed by the Company and that it fairly and accurately represents the information in the Covered Section.

Signed and dated this 13^thday of June 2024 at Johannesburg, South Africa.

Exhibit 107

Calculation of Filing Fee Tables

Form S-3

(Form Type)

NioCorp Developments Ltd.

(Exact Name of Registrant as Specified in its Charter)

Table 1—Newly Registered and Carry ForwardSecurities

(1) If any securities are issued in an amount denominatedin a foreign currency or composite currency, such amount as shall result in an aggregate initial offering price equivalent thereto inUnited States dollars at the time of initial offering.

(2) There are being registered on the registrationstatement on Form S-3 (the “Registration Statement”) to which this exhibit relates such indeterminate number of common shares,without par value (“Common Shares”), of NioCorp Developments Ltd. (the “Company”), Common Share purchase warrantsof the Company (“Warrants”) and units comprised of one or more of the other securities, or any combination thereof, of theCompany (“Units”), as shall have an aggregate initial offering price not to exceed $200,000,000. Any securities registeredunder the Registration Statement may be offered separately or in combination with the other securities registered under the RegistrationStatement. The securities being registered under the Registration Statement also include such intermediate number of Common Shares asmay be issued upon exercise of Warrants or pursuant to the anti-dilution provisions of such securities. In addition, pursuant to Rule416 under the Securities Act of 1933 (the “Securities Act”), the shares being registered under the Registration Statementinclude such indeterminate number of Common Shares as may be issuable with respect to the shares being registered under the RegistrationStatement as a result of stock splits, stock dividends or similar transactions.

(3) The proposed maximum aggregate offering priceper unit will be determined from time to time by the Company in connection with the issuance by the Company of the securities registeredunder the Registration Statement and is not specified as to each class of security pursuant to Item 16(b) of Form S-3 under the SecuritiesAct. In no event will the aggregate offering price of all securities sold by the Company from time to time pursuant to this RegistrationStatement exceed $200,000,000. No separate consideration will be received for Common Shares or other securities of the Company that maybe issued upon conversion or exercise of, as the case may be, the securities issued hereunder.

(4) Estimated solely for the purposes of computingthe amount of the registration fee pursuant to Rule 457(o) under the Securities Act.