【化】 紫刚玉

Amethyst \Am"e*thyst\, [F. ametiste, amatiste, F. am['e]thyste,
L. amethystus, fr. Gr. ? without drunkenness; as a noun, a
remedy for drunkenness, the amethyst, supposed to have this
power; 'a priv. + ? to be drunken, ? strong drink, wine. See
{Mead}.]
1. (Min.) A variety of crystallized quartz, of a purple or
bluish violet color, of different shades. It is much used
as a jeweler's stone.

{Oriental amethyst}, the violet-blue variety of transparent
crystallized corundum or sapphire.

2. (Her.) A purple color in a nobleman's escutcheon, or coat
of arms.

Corundum \Co*run"dum\ (k[-o]*r[u^]n"d[u^]m), n.; pl. {Corundums}
(k[-o]*r[u^]n"d[u^]mz). [Also corindon.] [From Hind. kurand
corundum stone.] (Min.)
The mineral alumina ({Al2O3}), as found native in a
crystalline state. Transparent varieties are used as
gemstones, 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.
[1913 Webster +PJC]

Note: The name corundum is sometimes restricted to the
non-transparent or coarser kinds. {Emery} is a
dark-colored granular variety, usually admixed with
magnetic iron ore.