Inventories

Inventories consisted of the following at December 31:



(In thousands)	2017		2016
Raw materials:
Drilling fluids	$	123,022	$	115,399
Mats	1,419		1,137
Total raw materials	124,441		116,536
Blended drilling fluids components	30,495		23,762
Finished goods - mats	10,400		3,314
Total inventories	$	165,336	$	143,612

Raw materials consist primarily of barite, chemicals, and other additives that are consumed in the production of our drilling fluid systems. Our blended drilling fluids components consist of base drilling fluid systems that have been either mixed internally at our mixing plants or purchased from third party vendors. These base drilling fluid systems require raw materials to be added, as needed to meet specified customer requirements.