| 释义 |
co·run·dum
\kəˈrəndəm\ noun
(-s)
Etymology: Tamil kuruntam, from Sanskrit kuruvinda ruby
: aluminum oxide Al2O3 occurring in nature in massive form and as variously colored rhombohedral crystals including the gems ruby, sapphire, oriental amethyst, oriental emerald, and oriental topaz, synthesized both in gem and industrial quality, extremely tough and with a hardness exceeded only by a few substances (as silicon carbide and diamond), and used industrially as an abrasive (hardness 9, specific gravity 3.95-4.10) |