Segment Information - Summary of segment information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024	Dec. 31, 2024
Australia segment operating income (expense):
Depreciation and amortization	$ (23)	$ (14)	$ (45)	$ (26)
Corporate administration	(678)	(779)	(1,976)	(2,035)
Gain on grant of royalty interest in mineral titles		16,909		16,909
Gain on sale of plant and equipment				802
Total operating income (expense), net	(2,485)	15,487	(5,343)	14,269
Non-operating income:
Interest income	140	163	309	266
Other income (expense)	(11)	(17)	(30)	25
Total non-operating income	129	146	279	291
Net income (loss)	(2,356)	15,633	(5,064)	14,560
Australia segment long-lived assets	1,626		1,626		$ 1,471
Corporate
Australia segment operating income (expense):
Corporate administration	(678)	(779)	(1,976)	(2,035)
Gain on grant of royalty interest in mineral titles		16,909		16,909
Gain on sale of plant and equipment				802
Australia segment | Operating segments
Australia segment operating income (expense):
Employee Compensation	(556)	(393)	(1,100)	(824)
2025 feasibility study and related costs	(850)		(1,589)
Drilling and related costs		(456)	(24)	(870)
Capitalized development costs		524	150	1,028
Project Programs	(129)	(57)	(181)	(183)
Site holding	(81)	(61)	(257)	(179)
Administrative	(93)	(106)	(178)	(183)
Consulting & contract services	(37)	(43)	(64)	(78)
Power	(38)	(37)	(79)	(92)
Depreciation and amortization	(23)	(14)	(45)	(26)
Total operating income (expense), net	(1,807)	(643)	(3,367)	(1,407)
Non-operating income:
Australia segment expenditures: mineral property and capital assets	16	$ 1,055	200	$ 1,110
Australia segment long-lived assets	$ 1,557		$ 1,557		$ 1,402