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Inventories (Tables)
3 Months Ended
Mar. 31, 2023
Inventory Disclosure [Abstract]  
Schedule of Inventories
Inventories are summarized as follows:
 MARCH 31
2023
 DECEMBER 31
2022
Coal$26,229 $27,927 
Mining supplies45,017 43,561 
 Total inventories$71,246  $71,488