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Note 8 - Inventories (Tables)
3 Months Ended
Mar. 31, 2022
Notes Tables  
Schedule of Inventory, Current [Table Text Block]
   

March 31,

   

December 31,

 
   

2022

   

2021

 

Coal

  $ 9,735     $ 12,078  

Supplies

    49,063       50,798  

Total Inventories

  $ 58,798     $ 62,876