Note 3 - Property, Plant and Equipment - Depreciation and amortization (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2025	Mar. 31, 2024
Property, Plant and Equipment.
Depreciation of plant and equipment	$ 10,365	$ 8,820
Amortization of right of use assets (finance leases)	1,892	2,493
Amortization and depletion of capitalized mine development costs and mineral rights	5,285	3,906
Total depreciation, depletion, and amortization	$ 17,542	$ 15,220

The aggregate amount of recurring noncash expense charged against earnings in the period to allocate the cost of assets over their estimated remaining economic lives.

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- Definition

The amount of expense recognized in the current period that reflects the allocation of the cost of tangible assets over the assets' useful lives. Includes production and non-production related depreciation.

+ References

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- Definition

The aggregate expense recognized in the current period that allocates the cost of tangible assets, intangible assets, or depleting assets to periods that benefit from use of the assets.

+ References

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- Definition

Amount of depreciation expense for lessor's underlying asset for which right to use has been conveyed to lessee under operating lease.

+ References

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- References

No definition available.

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