1. Badger Mining Corporation
2. Black Mountain Sand
LLC
3. CARBO Ceramics Inc.
4. Chongqing Changjiang River Moulding Material (Group) Co. Ltd.
5. Covia Holdings LLC
6. Diversity Technologies Corporation
7. Hi-Crush Inc.
8. LaPrairie Group of Companies
9. Mammoth Energy Service Inc.
10. Permian Frac Sand LLC
11. Preferred Proppants
LLC
12. SCR-Sibelco NV
13. Sierra Frac Sand
LLC
14. SmartSand Inc.
15. Superior Silica Sands
LLC