PROPERTY, PLANT, EQUIPMENT, AND MINERAL PROPERTIES

“Property, plant, equipment, and mineral properties, net" were comprised of the following (in thousands):



	March 31, 2015			December 31, 2014
Buildings and plant	$	269,090		$	268,032
Machinery and equipment	530,332			529,358
Vehicles	13,581			13,799
Office equipment and improvements	19,363			19,260
Ponds and land improvements	74,636			73,933
Total depreciable assets	907,002			904,382
Accumulated depreciation	(288,768		)	(271,294		)
Total depreciable assets, net	$	618,234		$	633,088

Mineral properties and development costs	$	163,741		$	163,197
Accumulated depletion	(19,508		)	(17,544		)
Total depletable assets, net	$	144,233		$	145,653

Land	909			909
Construction in progress	$	6,812		$	5,600
Total property, plant, equipment, and mineral properties, net	$	770,188		$	785,250

We incurred the following expenses for depreciation, depletion, and accretion, including expenses capitalized into inventory, for the following periods (in thousands):



	Three Months Ended March 31,
	2015		2014
Depreciation	$	18,879	$	18,260
Depletion	1,973		983
Accretion	424		406
Total incurred	$	21,276	$	19,649