Income taxes (Tables)

12 Months Ended

Dec. 31, 2025

Income Tax Disclosure [Abstract]

Components of income tax expense (benefit)

The Company’s loss before income taxes was attributable solely to domestic activities in the United States. The components of the Company’s income tax expense (benefit) were as follows (in thousands):

	Year Ended December 31,
	2025		2024
Current
Federal	$	—	$	—
Deferred
Federal	(8,170)		(13,786)
Change in Valuation Allowance	8,170		13,786
Income tax expense (benefit)	$	—	$	—

Schedule of effective income tax rate reconciliation

The following table provides a reconciliation of income taxes computed at the United States federal statutory tax rate of 21% in 2025 and 2024 to the income tax provision (dollars in thousands):

	Year Ended December 31,
	2025		2024
Loss before income taxes	$	(40,664)	$	(60,896)
United States statutory income tax rate	21%		21%
Income tax benefit at United States statutory income tax rate	(8,540)		(12,788)
Change in valuation allowance	8,170		13,786
Warrant fair value adjustment	(1)		—
Adjustment of prior year income taxes	264		(1,067)
Nondeductible expenses	107		69
Income tax expense (benefit)	$	—	$	—

Components of deferred tax assets

The components of the Company’s deferred tax assets are as follows (in thousands):

	Year Ended December 31,
	2025		2024
Net operating loss	$	80,863	$	74,056
Mineral properties	56,198		52,303
Plant, equipment, and mine development	1,687		1,415
Intangible assets	14,181		15,687
Deferred gain on sale of royalty	6,266		6,266
Asset retirement obligation	2,472		2,762
Interest expense carryforward	8,799		9,156
Accrued compensation	663		629
Stock-based compensation	1,927		1,998
Inventories	943		947
Assets held-for-sale	(39)		476
Other	895		990
Valuation allowance	(174,855)		(166,685)
Total	$	—	$	—

Summary of operating loss carryforwards

In connection with multiple equity offerings during 2022 and 2025, the Company underwent the following Section 382 ownership changes (in thousands):

Tax Loss Carryovers		Year Ended December 31,
Ownership Change Date	Annual Limitation	2025		2024
March 25, 2022	$1,300	$	306,830	$	299,743
June 13, 2025	3,066	64,332		N/A
October 9, 2025	7,229	7,620		N/A