Inventories

The major components of inventories were as follows:



	March 31, 2018		December 31, 2017
Petroleum products	$	20,048	$	8,731
Crude oil	25,133		29,873
Caustic soda	5,016		5,755
NaHS	9,655		8,277
Raw materials - Alkali operations	4,648		4,550
Work-in-process - Alkali operations	9,747		7,355
Finished goods, net - Alkali operations	10,914		14,075
Materials and supplies, net - Alkali operations	10,498		10,030
Other	8		7
Total	$	95,667	$	88,653

Inventories are valued at the lower of cost or net realizable value. The net realizable value of inventories were not below cost as of March 31, 2018 and December 31, 2017.