出典:Wiktionary
出典:『Wiktionary』 (2024/08/24 21:28 UTC 版)
corundum (countable and uncountable, plural corundums)
出典:Wikipedia
出典:『Wikipedia』 (2011/06/24 04:40 UTC 版)
Corundum is a crystalline form of aluminium oxide (Al2O3) with traces of iron, titanium and chromium. It is a rock-forming mineral. It is one of the naturally clear transparent materials, but can have different colors when impurities are present. Transparent specimens are used as gems, called ruby if red and padparadscha if a pink-orange, while all other colors are called sapphire.