emery

corundum

corundum (kərŭnˈdəm), mineral, aluminum oxide, Al₂O₃. The clear varieties are used as gems and the opaque as abrasive materials. Corundum occurs in crystals of the hexagonal system and in masses. It is transparent to opaque and has a vitreous to adamantine luster. The transparent gem varieties are colorless, pink, red, blue, green, yellow, and violet; the common varieties are blue-gray to brown. Emery is a common corundum, used as an abrasive and distinguished by its impurities of magnetite and hematite. The chief corundum gems are the ruby (red) and the sapphire (blue). Yellow, pink, green, and white stones are also called yellow, pink, green, and white sapphires. Corundum gems are also made synthetically. The chief sources of natural corundum are Myanmar, Sri Lanka, India, Thailand, Republic of South Africa, Tanzania, and the United States (North Carolina, Georgia, and Montana). Most of the emery is mined in Naxos and the other Cyclades and in Asia Minor.

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The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Emery

 

fine-grained rock in which the corundum is closely interlocked with such minerals as magnetite, sulfides, and brittle mica. Containing up to 60 percent corundum, emery is one of the natural abrasive materials. Emery has a hardness of 7–8 on the mineralogical scale. It is found chiefly in marble in the form of lenses, stocks, nests, and veins. Less frequently emery occurs in the form of xenolith in gabbro, norite, and granite or at the contact between these rocks and enclosing rock.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.

emery

[′em·ə·rē]

(materials)

An abrasive which is composed of pulverized, impure corundum; used in polishing and grinding.

(mineralogy)

A fine, granular, gray-black, impure variety of corundum containing iron oxides, either hematite or magnetite; occurs as masses in limestone and as segregations in igneous rock.

McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

emery

A granular form of impure carborundum; used for grinding and polishing glass, stone, and metal surfaces.

McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc.

emery

a. a hard greyish-black mineral consisting of corundum with either magnetite or haematite: used as an abrasive and polishing agent, esp as a coating on paper, cloth, etc. Formula: Al₂O₃

b. (as modifier): emery paper

Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005