December 31,

2023

2022

(in thousands)

Mining equipment and processing facilities

$

1,989,541

$

1,927,603

Land and coal mineral rights

504,736

499,950

Oil & gas mineral interests

853,350

814,667

Buildings, office equipment, improvements and other miscellaneous equipment

310,876

300,436

Construction, mine development and other projects in progress

184,895

99,042

Mine development costs

329,146

289,724

Property, plant and equipment, at cost

4,172,544

3,931,422

Less accumulated depreciation, depletion and amortization

(2,149,881)

(2,050,754)

Total property, plant and equipment, net

$

2,022,663

$

1,880,668