Extremely hard crystallized alumina, used as an abrasive. Ruby and sapphire are varieties of corundum.
More example sentences
- Although blue corundum, zircon, and tourmaline occur in Colorado, they are not known to produce gems.
- Red gem-quality corundum is known as ruby; all other colors of gem corundum are referred to as sapphire, with a prefix denoting the color of the stone.
- Several Colorado gem minerals (lazurite and the state's minor occurrences of corundum and cordierite) form in metamorphic rocks.
Definition of corundum in:
- The US English dictionary