Note 2 - Business Segments and Sales of Products - Sales of Products (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Segment Reporting, Revenue Reconciling Item [Line Items]
Total sales	$ 245,085	$ 181,906	$ 680,270	$ 559,537
Less: Smelter and refining charges	(10,518)	(12,550)	(32,814)	(40,743)
Silver Contracts [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Total sales	109,756	74,425	308,681	235,447
Gold [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Total sales	79,239	70,206	229,123	208,216
Lead [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Total sales	21,591	15,719	65,002	62,778
Zinc [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Total sales	37,281	33,066	94,741	91,912
Copper [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Total sales	409	0	409	0
Total Metal [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Total sales	237,758	180,866	665,142	557,610
Environmental Remediation Services [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Total sales	$ 7,327	$ 1,040	$ 15,128	$ 1,927