Note 3 - Property, Plant and Equipment - Schedule of Property, Plant and Equipment (Details) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Property, plant, and equipment
Less: Accumulated depreciation and amortization	$ (95,618)	$ (80,269)
Total property, plant and equipment, net	341,596	227,077
Capitalized Costs Related to Coal Reserves	28,400	25,100
Plant and Equipment
Property, plant, and equipment
Property, plant and equipment, gross	187,781	167,019
Mining Properties and Mineral Rights
Property, plant, and equipment
Property, plant and equipment, gross	90,081	26,064
Construction in Progress
Property, plant, and equipment
Property, plant and equipment, gross	32,659	9,972
Capitalized mine development cost
Property, plant, and equipment
Property, plant and equipment, gross	$ 126,693	$ 104,291

The amount of costs capitalized related to coal reserves.

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Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

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Amount before accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

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Amount after accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business to produce goods and services and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

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