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Note 7 - Inventories (Tables)
6 Months Ended
Jun. 30, 2022
Notes Tables  
Schedule of Inventory, Current [Table Text Block]
   

June 30,

   

December 31,

 
   

2022

   

2021

 

Coal

  $ 14,974     $ 12,078  

Supplies

    53,469       50,798  

Total Inventories

  $ 68,443     $ 62,876