COMMON SHARES (Details Narrative)				12 Months Ended
	Jun. 09, 2023 USD ($) shares	Apr. 28, 2023 USD ($) shares	Nov. 05, 2020	Jun. 30, 2023 USD ($) shares	Jun. 30, 2022 USD ($) $ / shares shares	Jun. 30, 2023 $ / shares
Subsidiary, Sale of Stock [Line Items]
Warrants | shares		314,465
Shares issue price		$ 2,000,000.0
Share issuance cost		$ 172,000
Stock price | $ / shares						$ 6.68
Description of warrants				The Company may elect to redeem the Public Warrants subject to certain conditions, in whole and not in part, at a price of $0.01 per Public Warrant if (i) 30 days’ prior written notice of redemption is provided to the holders, (ii) the last reported sale price of the Common Shares equals or exceeds approximately $16.10 per share (as adjusted for stock splits, stock dividends, reorganizations, recapitalizations and the like) for any 20 trading days within a 30-trading day period ending on the third business day prior to the date on which the Company sends the notice of redemption to the warrant holders
GXII Public Warrants [Member]
Subsidiary, Sale of Stock [Line Items]
Warrants traded prior to the closing | shares				9,999,959
GXII Private Warrants [Member]
Subsidiary, Sale of Stock [Line Items]
Warrants traded prior to the closing | shares				5,666,667
Long TermIncentive Plan [Member]
Subsidiary, Sale of Stock [Line Items]
Description of amended plan			Subject to adjustment as described in the 2017 Amended Long-Term Incentive Plan, the aggregate number of Common Shares that may be reserved for issuance to participants under the 2017 Amended Long-Term Incentive Plan, together with all other security-based compensation arrangements of the Company, may not exceed 10% of the issued and outstanding Common Shares from time to time, and the Common Shares reserved for issuance upon settlement of share units will not exceed 5% of the issued and outstanding Common Shares from time to time. The 2017 Amended Long-Term Incentive Plan limits the maximum number of Common Shares issued to insiders (as defined under TSX rules for this purpose) within any one-year period, or issuable to insiders at any time, in the aggregate, under all security-based compensation arrangements (including the 2017 Amended Long-Term Incentive Plan) to 10% of the then issued and outstanding Common Shares.
Warrant [Member]
Subsidiary, Sale of Stock [Line Items]
Description of warrants				Each NioCorp Assumed Warrant entitles the holder to the right to purchase 1.11829212 Common Shares at an exercise price of $11.50 per 1.11829212 Common Shares (subject to adjustments for stock splits, stock dividends, reorganizations, recapitalizations and the like).
Canada, Dollars
Subsidiary, Sale of Stock [Line Items]
Total intrinsic value				$ 1,592
Private Placement [Member] | Canada, Dollars
Subsidiary, Sale of Stock [Line Items]
Warrants | shares					498,103
Price per unit | $ / shares					$ 0.96
Gross proceeds					$ 4,800,000
Shares price | $ / shares					$ 1.10
Private Placement [Member] | Canada, Dollars | Warrant [Member]
Subsidiary, Sale of Stock [Line Items]
Warrants | shares					6,510
Gross proceeds					$ 18
Cash commissions					$ 62
Risk-free rate					3.20%
Expected volatility					64.00%
Expected life					2 years
Yorkville Convertible Debt Financing Agreement [Member]
Subsidiary, Sale of Stock [Line Items]
Warrants | shares	100,000
Share issuance cost	$ 13,000