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Inventories (Tables)
9 Months Ended
Sep. 30, 2023
Inventory Disclosure [Abstract]  
Schedule of Inventories
Inventories are summarized as follows:
 SEPTEMBER 30
2023
 DECEMBER 31
2022
Coal$17,765 $27,927 
Mining supplies51,451 43,561 
 Total inventories$69,216  $71,488