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Property, Plant, and Equipment, net
 12 Months Ended
Dec. 31, 2023
Property, Plant and Equipment [Abstract]  
Property, Plant, and Equipment, net Property, Plant, and Equipment, net
Property, plant, and equipment, net, consisted of the following: 
December 31,
 20232022
Plant and mining equipment$890,327 $723,056 
Mine development162,285 130,144 
Land32,033 27,937 
Office equipment, software and other5,356 3,111 
Construction in progress57,896 49,583 
Total property, equipment and mine development costs$1,147,897 $933,831 
Less accumulated depreciation and amortization(558,905)(491,186)
Total property, plant, and equipment, net$588,992 $442,645 
Included in plant and mining equipment are assets under financing leases totaling $10,964 and $13,139 with accumulated depreciation of $5,015 and $7,710 as of December 31, 2023 and 2022, respectively.
Depreciation and amortization expense associated with property, plant, equipment and non-mineral asset retirement obligation assets, net, was $112,925, $84,542, and $86,506 for the years ended December 31, 2023, 2022, and 2021 respectively.

Depreciation expense for the years ended December 31, 2023, 2022, and 2021 includes an expense of $7,343, and credits of ($1,344) and ($307), respectively, related to revisions to asset retirement obligations. Refer to Note 15 for further disclosures related to asset retirement obligations.
As of December 31, 2023, the Company had unconditional purchase obligations for approximately $48,557 of new equipment purchase commitments expected to be acquired at various dates in 2024.