Periclase

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periclase

[′per·ə‚klās]
(mineralogy)
MgO Native magnesia; a mineral occurring in granular forms or isometric crystals, with hardness of 6 on Mohs scale, and specific gravity of 3.67-3.90. Also known as periclasite.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Periclase

 

a mineral that consists of natural magnesium oxide (MgO) with occasional admixtures of FeO, MnO, and ZnO. Periclase, whose crystal structure resembles that of rock salt, crystallizes in the isometric system to form cubic and octahedral crystals as well as irregular grains; cleavage is perfect along the cube. Periclase is grayish white, yellow, dark green, or black with a hardness of 5.5–6 on Mohs’ scale and a density that ranges from 3,600 to 3,900 kg/m3. It is characteristic of meta-morphic limestones and dolomites. As a result of weathering, periclase alters to brucite and hydromagnesite. Artificial periclase, which is usually prepared by sintering natural magnesite at 1600”-1650oC or by electrically smelting natural magnesite, is important in manufacturing magnesite refractories.

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

periclase

A crystalline mineral which is sometimes found in portland cement, portland cement clinker, and certain slags.
McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc.