1. US Silica Holdings Inc.
2. Compagnie de Saint-Gobain S.A
3. Smart Sand Inc.
4. Badger Mining Corporation
5. Xinmi Wanli Industry Development Co. Ltd.
6. Petro Welt Technologies AG
7. Minera??o Curimbaba Ltda
8. Vikas Proppants & Granite Limited
9. Nika Petro Tech
10. JSC Borovichi Refractories Plant.