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(mär`kəsīt) or

white iron pyrites,

a mineral closely resembling and having the same chemical composition (FeS2) as pyritepyrite
or iron pyrites
, pale brass-yellow mineral, the bisulfide of iron, FeS2. It occurs most commonly in crystals (belonging to the isometric system and usually in the form of cubes and pyritohedrons) but is also found in massive, granular, and stalactite
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. It differs from pyrite in that it is paler in color, becomes darker upon oxidation, and crystallizes in the orthorhombic system. Twinned crystals resembling cockscombs (cockscomb pyrites) or spearheads (spear pyrites) are of common occurrence. The mineral occurs in marls, clays, and limestones in many parts of the world.
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The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



(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.


Mineraly; Spravochnik, vol. 1. Moscow, 1960.
The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.


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.


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
References in periodicals archive ?
Field evidence, ore microscopy, and electron microprobe analyses of the lodes suggest that the vein mineralization commenced with pre-ore precipitation of diagenetic marcasite, pyrite, and minor gel-like colloform textured schalenblende and galena particularly in the vein--wall contacts (Akande and Mucke, 1993).
Mumin, "Gold-bearing arsenian pyrite and marcasite and arsenopyrite from Carlin Trend gold deposits and laboratory synthesis," American Mineralogist, vol.
I Minerals identified 1 20.866 4.254 17.60 Quartz 2 25.996 3.425 69.27 Barite/galena/ marcasite 3 26.791 3.326 31.79 Sphalerite/quartz/cinnabar 4 28.824 3.096 100.00 Sphalerite/calcite/barite/chalcopyrite 5 30.410 2.938 8.21 Galena 6 33.322 2.687 36.35 Arsenopyrite/pyrite/marcasite 7 36.081 2.4878 6.55 Barite 8 37.343 2.407 16.43 Barite/marcasite/arsenopyrite/pyrite 9 47.736 1.904 51.75 Sphalerite//calcite 10 52.160 1.753 10.99 Galena/ marcasite/ quartz 11 54.451 1.684 12.50 Sphalerite 12 56.540 1.627 33.22 Pyrite/sphalerite 13 76.769 1.241 14.80 Sphalerite Table 3.
previously such as mixing stones like marcasite and rhinestone with crystal and enamel.
It has been identified as a particularly conductive marcasite containing the narrow 3d band (about 1.1 eV).
Until January 1, fashionistas who shop online during the Charles David 70% sale on women's fashion can save big on a variety of designs in a multitude of colors and sizes, including: Marcasite, Tasset, Tansy, Buckie, Desi, Mateo, Toro, Amado, Solstice, Solace, Galactic, Ritz, Posh, Rapture and dozens more.
Iron sulphates of marcasite and pyrite can also be found along with lime in some high iron content clays.
8, Necklace in silver with marcasite, POMELLATO, Bamboo cuff in sterling silver, GUCCI, Make Love Not War silver ring, EEVA ATTLING, Divorced with Children silver ring, EFVA ATTLING, Perlee white gold ring.
The going was testing, but they managed to complete the card in conditions that proved just the ticket for Mister Marcasite, who shaped well on soft ground on his first two starts but flopped on quicker ground since.
Sterling Silver Marcasite & Garnet Glass Heart Pendant: [begin