marcasite

marcasite

a metallic pale yellow mineral consisting of iron sulphide in orthorhombic crystalline form used in jewellery. Formula: FeS₂

Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005

marcasite

[′mär·kə‚sīt]

(mineralogy)

FeS₂ A pale bronze-yellow to nearly white mineral, crystallizing in the orthorhombic system; hardness is 6-6.5 on Mohs scale, and specific gravity is 4.89.

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 It might be outdated or ideologically biased.

Marcasite

 

(also white iron pyrite), a mineral, a polymorphic variety of natural disulfide of iron, FeS₂. Marcasite crystallizes in the orthorhombic system. The luster is metallic. Of bronze-yellow color, which changes to gray along the crystal surface, the mineral forms spear-shaped, often complex, twin crystals, comb-like and round concretions, or sooty black masses (melnikovitemarcasite). Marcasite has a hardness of 6-6.5 on Mohs’ scale and a density of 4,850- 4,900 kg/m³. It usually forms from natural subacid solutions at temperatures lower than the temperature at which pyrite forms. Marcasite is found in hydrothermal deposits in association with pyrite, pyrrhotite, and other sulfides; it often replaces pyrrhotite in the oxidized zone of sulfide deposits. Marcasite occurring in sedimentary rocks is particularly widespread in Carboniferous deposits containing sand and clay, where it forms irregular nodular and concretionary formations. The mineral is used in the preparation of sulfuric acid.

REFERENCE

Mineraly; Spravochnik, vol. 1. Moscow, 1960.

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