December 31,

2022

2021

(in thousands)

Mining equipment and processing facilities

$

1,927,603

$

1,896,470

Land and coal mineral rights

499,950

458,440

Oil & gas mineral interests

740,635

647,864

Buildings, office equipment, improvements and other miscellaneous equipment

300,436

282,902

Construction, mine development and other projects in progress

99,042

44,217

Mine development costs

289,724

278,454

Property, plant and equipment, at cost

3,857,390

3,608,347

Less accumulated depreciation, depletion and amortization

(2,040,468)

(1,909,669)

Total property, plant and equipment, net

$

1,816,922

$

1,698,678