The most typical sort of crystalline alumina, α-aluminium oxide, is referred to as corundum. When trace things ensure it is seem red it is named ruby, but all other colorations fall under the designation sapphire. Corundum has a trigonal Bravais lattice with a space team of R-3c (variety 167 inside https://diamondpaste87542.life3dblog.com/33742859/a-review-of-aluminum-oxide