| 501 / | HD | COMPOSITIONS: CERAMIC |
| 1 | DF | CERAMIC COMPOSITIONS {15} |
| 11 | DF | .~ Glass compositions, compositions containing glass other than those wherein glass is a bonding agent, or glass batch forming compositions {11} |
| 53 | DF | .~.~ Silica containing {3} |
| 55 | DF | .~.~.~ 40 percent - 90 percent by weight silica {7} |
| 68 | | .~.~.~.~ And aluminum or iron compound {1} |
| 69 | DF | .~.~.~.~.~> And divalent metal oxide (e.g., oxides of zinc, cadmium, beryllium, alkaline earth metal, magnesium, etc.) {1} |