1. Also called white iron pyrites. a common mineral, iron disulfide, FeS2, chemically similar to pyrite but crystallizing in the orthorhombic system.
  2. any of the crystallized forms of iron pyrites, much used in the 18th century for ornaments.
  3. a specimen or ornament of this substance.

Origin of marcasite

1375–1425; late Middle English < Medieval Latin marcasīta < Arabic marqashīṭā < Aramaic marqəshītā
Related formsmar·ca·sit·i·cal [mahr-kuh-sit-i-kuh l] /ˌmɑr kəˈsɪt ɪ kəl/, adjective Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

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Historical Examples of marcasite

British Dictionary definitions for marcasite


  1. a metallic pale yellow mineral consisting of iron sulphide in orthorhombic crystalline form used in jewellery. Formula: FeS 2
  2. a cut and polished form of steel or any white metal used for making jewellery
Derived Formsmarcasitical (ˌmɑːkəˈsɪtɪkəl), adjective

Word Origin for marcasite

C15: from Medieval Latin marcasīta, from Arabic marqashītā, perhaps from Persian
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for marcasite

crystalized pyrite, early 15c., from Medieval Latin marchasita, of obscure origin, perhaps via Spanish, probably from Arabic, though OED doubts this. Perhaps ultimately from Persian marquashisha [Klein]. "This name has been used for a number of substances but mainly for iron pyrites and especially for the crystalline forms used in the 18th century for ornaments." [Flood]

Online Etymology Dictionary, © 2010 Douglas Harper

marcasite in Science


[märkə-sīt′, -zīt′]
  1. A light yellow to gray, metallic, orthorhombic mineral. Marcasite is a polymorph of pyrite and looks similar to it but has a lower specific gravity, is paler in color, and often has a radiating fibrous structure. Chemical formula: FeS2.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.