Carbo Ceramics Inc.
COVIA
JSC Borovichi Refractories Plant
S. Silica Holdings Inc.
Hi-Crush Inc.
Minera??oCurimbaba
XinmiWanli Industry Development Co. Ltd.
Atlas Sand Company
LLC
HEXION
Schlumberger Ltd.
Select Sands Corporation
Preferred Sands
U.S. Silica Holdings Inc.
Emerge Energy Services LP
Badger Mining Corporation