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Mineral Leaseholds, Net (Tables)
3 Months Ended
Mar. 31, 2021
Extractive Industries [Abstract]  
Mineral Leaseholds, Net of Accumulated Depletion
Mineral leaseholds, net of accumulated depletion, consisted of the following:
March 31,
2021
December 31,
2020
Mineral leaseholds$1,335 $1,333 
Less: accumulated depletion(540)(530)
Mineral leaseholds, net$795 $803