Clues for the word "CORUNDUM"

We've had 4 crossword clues used for this word, and seen it 3 times in crosswords. It was last seen in LA Times crossword on September 02, 2022.

Definition of corundum

n. - The earth alumina, as found native in a crystalline state, including sapphire, which is the fine blue variety; the oriental ruby, or red sapphire; the oriental amethyst, or purple sapphire; and adamantine spar, the hair-brown variety. It is the hardest substance found native, next to the diamond.