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The Collaborative International Dictionary of English v.0.48 (gcide)

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.
[1913 Webster]


Emery \Em"er*y\, n. [F. ['e]meri, earlier ['e]meril, It.
smeriglio, fr. Gr. ?, ?, ?, cf. ? to wipe; perh. akin to E.
smear. Cf. {Emeril}.] (Min.)
Corundum in the form of grains or powder, used in the arts
for grinding and polishing hard substances. Native emery is
mixed with more or less magnetic iron. See the Note under
{Corundum}.
[1913 Webster]

{Emery board}, cardboard pulp mixed with emery and molded
into convenient.

{Emery cloth} or {Emery paper}, cloth or paper on which the
powder of emery is spread and glued for scouring and
polishing.

{Emery wheel}, a wheel containing emery, or having a surface
of emery. In machine shops, it is sometimes called a {buff
wheel}, and by the manufacturers of cutlery, a {glazer}.
[1913 Webster]