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Note 9 - Inventories (Tables)
12 Months Ended
Dec. 31, 2021
Notes Tables  
Schedule of Inventory, Current [Table Text Block]
  

December 31,

 
  

2021

  

2020

 

Coal

 $12,078  $7,163 

Supplies

  50,798   49,037 

Total Inventories

 $62,876  $56,200