Note 11 - Segment Reporting - Reconciliation of operating profit and capital expenditure (Details)	3 Months Ended
Mar. 31, 2025 USD ($)	Mar. 31, 2024 USD ($)
SEGMENT REPORTING
Number of Operating Segments	1
Number of Reportable Segments	1
Cash cost of sales (FOB mine)	$ 92,763,000	$ 109,465,000
Transportation costs	18,998,000	28,876,000
Alternative mineral development costs	1,912,000	1,135,000
Other cost of sales	459,000	237,000
Cost of sales	114,132,000	139,713,000
Total capital expenditures (including accrued capital expenditures)	$ 21,452,000	$ 19,929,000

Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues.

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 49
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482785/280-10-55-49

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 18
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-18

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