Note 2 - Business Segments and Sales of Products - Sales of Products (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Segment Reporting, Revenue Reconciling Item [Line Items]
Total sales	$ 304,027	$ 245,657	$ 565,366	$ 435,185
Less: Smelter and refining charges	(2,544)	(9,282)	(9,256)	(22,296)
Silver Contracts [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Total sales	122,661	112,692	240,814	198,925
Gold [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Total sales	123,721	82,469	210,909	149,884
Lead [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Total sales	21,476	23,928	43,582	43,411
Zinc [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Total sales	31,138	32,496	64,263	57,460
Copper [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Total sales	979	0	1,370	0
Total Metal [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Total sales	297,431	242,303	551,682	427,384
Environmental Remediation Services [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Total sales	$ 6,596	$ 3,354	$ 13,684	$ 7,801