Inventories

Inventories consisted of the following:



(In thousands)	March 31, 2018		December 31, 2017
Raw materials:
Drilling fluids	$	146,021	$	123,022
Mats	1,511		1,419
Total raw materials	147,532		124,441
Blended drilling fluids components	32,510		30,495
Finished goods - mats	9,067		10,400
Total inventory	$	189,109	$	165,336

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. As described in Note 1, the adoption of the new revenue recognition guidance resulted in a $5.5 million increase in inventories as of January 1, 2018.