Depreciation on property, plant and equipment is recognized on a straight-line basis over their estimated useful lives, as follows:
Years
Land improvements
10-25
Buildings and building improvements
10-40
Machinery and equipment
3-20
The Company’s property, plant and equipment consisted of the following:
December 31,
(in thousands)20252024
Land and land improvements$43,422 $42,789 
Buildings and building improvements101,564 96,961 
Machinery and equipment756,202 662,333 
Assets under construction302,935 202,544 
Mineral rights438,395 438,395 
Property, plant and equipment, gross1,642,518 1,443,022 
Less: Accumulated depreciation and depletion(272,701)(191,526)
Property, plant and equipment, net$1,369,817 $1,251,496 
The Company’s depreciation and depletion expense, net of amounts capitalized into inventories, was as follows:
For the year ended December 31,
(in thousands)202520242023
Depreciation expense
$69,587 $63,558 $43,998 
Depletion expense
$6,724 $13,036 $11,067 

Historical Timeline

Fiscal YearFiled
2025Feb 26, 2026Showing above
2024Feb 28, 2025
2023Feb 28, 2024

About PP&E Disclosures

The PP&E disclosure details a company's physical asset base — land, buildings, machinery, and equipment — along with the depreciation methods and useful life assumptions that determine how these costs flow through the income statement. Capitalization policy thresholds reveal management's judgment on the boundary between expense and asset, directly affecting both reported earnings and asset values.

Key signals: changes in estimated useful lives or depreciation methods can materially shift reported earnings without any operational change. Compare capital expenditures against depreciation expense — when capex consistently trails depreciation, the asset base may be aging and underinvested. Watch for large asset impairments or write-downs that signal overvalued carrying amounts. Asset retirement obligations reveal future environmental or decommissioning costs that are often underappreciated. Compare PP&E intensity (PP&E-to-revenue) against industry peers to assess capital efficiency and competitive positioning.