Note 6 - Income and Mining Taxes - Schedule of Effective Income Tax Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Computed "statutory" benefit (provision), Amount	$ 9,432	$ (1,161)	$ 264
Computed “statutory” benefit (provision), Percentage	21.00%	21.00%	21.00%
Percentage depletion, Amount	$ 8,542	$ 8,076	$ 5,327
Percentage depletion, Percentage	19.00%	(146.00%)	423.00%
Change in valuation allowance, Amount	$ (8,113)	$ 38,058	$ 786
Change in valuation allowance, Percentage	(18.00%)	(689.00%)	62.00%
State taxes, net of federal tax benefit, Amount	$ (158)	$ 965	$ (1,164)
State taxes, net of federal tax benefit, Percentage	0.00%	(17.00%)	(93.00%)
Foreign currency remeasurement of monetary assets and liabilities, Amount	$ (4,559)	$ (3,625)	$ (4,824)
Foreign currency remeasurement of monetary assets and liabilities, Percentage	10.00%	66.00%	(383.00%)
Rate differential on foreign earnings, Amount	$ 1,515	$ 2,445	$ 2,362
Rate differential on foreign earnings, Percentage	3.00%	(44.00%)	188.00%
Compensation, Amount	$ 173	$ 1,094	$ (458)
Compensation, Percentage	0.00%	(20.00%)	(36.00%)
Mining and other taxes, Amount	$ (6,609)	$ (13,799)	$ (9,245)
Mining and other taxes, Percentage	(15.00%)	250.00%	(735.00%)
Other, Amount	$ (1,775)	$ (2,484)	$ (1,247)
Other, Percentage	(3.00%)	45.00%	(99.00%)
Total income and mining tax benefit (provision)	$ 7,566	$ 29,569	$ (8,199)
Total benefit (provision), Percentage	17.00%	(535.00%)	(652.00%)