
	Useful Lives (Years)	December 31,
		2025		2024
Land	—	$	265,587	$	295,176
Land improvements	10 – 30	351,394		342,213
Buildings and improvements	10 – 50	936,635		933,188
Machinery and equipment(a)	2 – 45	7,812,518		8,187,422
Mineral rights and reserves	7 – 60	1,759,775		1,755,770

Construction in progress	—	642,931		1,009,599
Total		$	11,768,840	$	12,523,368

(a)Consists primarily of (1) short-lived production equipment components, office and building equipment and other equipment with estimated lives ranging 2 – 7 years, (2) production process equipment (intermediate components) with estimated lives ranging 8 – 19 years, (3) production process equipment (major unit components) with estimated lives ranging 20 – 29 years, and (4) production process equipment (infrastructure and other) with estimated lives ranging 30 – 45 years.

The cost of property, plant and equipment is depreciated generally by the straight-line method. Depletion of mineral rights is based on the units-of-production method. Depreciation expense, including depletion, amounted to $632.4 million, $561.4 million and $398.5 million during the years ended December 31, 2025, 2024 and 2023, respectively. Interest capitalized on significant capital projects in 2025, 2024 and 2023 was $18.5 million, $49.0 million and $72.7 million, respectively.

In 2022, the Company announced it has been awarded a nearly $150 million grant from the U.S. Department of Energy to expand domestic manufacturing of batteries for EVs and the electric grid and for materials and components currently imported from other countries. The grant funding is intended to support a portion of the anticipated cost to construct a new, commercial-scale U.S.-based lithium concentrator facility at our Kings Mountain, North Carolina location. The grant will be received over the life of the construction period for the new facility (projected through 2028) as reimbursement for capital expenditures. To further support the restart of the Kings Mountain mine, in 2023, we announced a $90 million critical materials award from the U.S. Department of Defense. As funds are received for both of these grants, the Company will reduce the cost of the assets by the amount of the grant, and income will be recognized by the lower depreciation expense over the useful life of the assets. During the years ended December 31, 2025 and 2024, the Company received $12.8 million and $12.4 million of these funds, respectively, which reduced the cost of Property, plant and equipment on the balance sheet.