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Note 9 - Inventories (Tables)
6 Months Ended
Jun. 30, 2021
Notes Tables  
Schedule of Inventory, Current [Table Text Block]
  

June 30,

  

December 31,

 
  

2021

  

2020

 

Coal

 $12,457  $7,163 

Supplies

  46,842   49,037 

Total Inventories

 $59,299  $56,200