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INVENTORIES (Details) - USD ($)
$ in Thousands
Mar. 31, 2023
Dec. 31, 2022
INVENTORIES    
Coal $ 50,406 $ 23,553
Supplies (net of reserve for obsolescence) 58,242 53,773
Total inventories, net 108,648 77,326
Reserve for obsolescence $ 6,967 $ 6,601