| Silicon Oxide | Aluminum Oxide | Magnesium Oxide |
| Titanium Oxide | Zirconium Oxide |
| American Elements | Channel Industries | CIMBAR Performance Minerals |
| Corning Incorporated | Gouda Vuurvast | Minelco Inc. |
| NanoScale | Potters Industries | Pyrotek, Inc. |
| Trelleborg | Von Roll Isola | Wieland |