| 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} |
| 73 | DF | .~.~.~ Less than 40 percent by weight silica {2} |
| 77 | | .~.~.~.~ And boron {2} |
| 78 | DF | .~.~.~.~.~> And rare earth (i.e., elements with atomic number 39 or 57-71) |
| 79 | DF | .~.~.~.~.~> And zinc |