1. Aegean Perlites SA
2. Amol Minechem Limited
3. AUSPERL Pty. Ltd.
4. Carolina Perlite Co. Inc.
5. Cevahir Perlite
6. Dicalite Management Group Inc.
7. Genper
8. Goodwin PLC
9. Gulf Perlite LLC
10. Imerys S.A.
11. IPM Industries
12. Keltech Energies Limited
13. Midwest Perlite
14. NorCal Perlite Inc.
15. Omya International AG
16. Pennsylvania Perlite Corporation
17. Perlite Vermiculite Packaging Industries Inc.
18. Perlite-Hellas
19. Procema Perlit SRL
20. Profiltra B.V.
21. Saudi Perlite Industries
22. Silbrico Corporation
23. Supreme Perlite
24. The Schundler Company
25. U.S. Silica Holdings Inc.
26. Whittemore Company Inc.