PROPERTY, PLANT, EQUIPMENT AND MINERAL PROPERTIES (Tables)

12 Months Ended

Dec. 31, 2019

Property, Plant and Equipment [Line Items]

Schedule of Property, Plant, Equipment, And Mineral Properties

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

	December 31,
	2019			2018
Land	$	27,274		$	519
Ponds and land improvements	65,992			58,961
Mineral properties and development costs	143,988			139,418
Buildings and plant	81,468			81,429
Machinery and equipment	253,536			241,977
Vehicles	6,222			5,669
Office equipment and leasehold improvements	9,136			13,779
Operating lease ROU assets	8,123			—
Construction in progress	7,124			2,822
Total property, plant, equipment, and mineral properties, gross	$	602,863		$	544,574
Less: accumulated depreciation, depletion, and amortization	(224,354		)	(198,365		)
Total property, plant, equipment, and mineral properties, net	$	378,509		$	346,209

Schedule of Depreciation, Depletion Amortization and Accretion

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

	Year Ended December 31,
	2019		2018		2017
Depreciation	$	27,889	$	27,858	$	28,323
Depletion	4,173		4,357		4,886
Amortization of ROU assets	2,059		—		—
Total incurred	$	34,121	$	32,215	$	33,209