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 (mär′kə-sīt′, -zīt′)
1. A mineral with the same composition as pyrite, FeS2, but differing in crystal structure. Also called white iron pyrites.
2. An ornament of pyrite, polished steel, or white metal.

[Middle English, from Medieval Latin marcasīta, from Arabic marqašīṯā, from Aramaic marqəšitā, from Akkadian marḫašu, from marḫaši, ancient region in the eastern Iranian plateau.]

mar′ca·sit′i·cal (-sĭt′ĭ-kəl) adj.


1. (Minerals) a metallic pale yellow mineral consisting of iron sulphide in orthorhombic crystalline form used in jewellery. Formula: FeS2
2. (Jewellery) a cut and polished form of steel or any white metal used for making jewellery
[C15: from Medieval Latin marcasīta, from Arabic marqashītā, perhaps from Persian]
marcasitical adj


(ˈmɑr kəˌsaɪt)

1. a common mineral, iron sulfide, FeS2, chemically identical to pyrite but crystallizing in the orthorhombic system.
a. a crystallized form of this, used for jewelry.
b. any mineral resembling this form or any substance imitating it, esp. as used in jewelry.
[1375–1425; < Medieval Latin marcasīta < Arabic < Aramaic]
mar`ca•sit′i•cal (-ˈsɪt ɪ kəl) adj.
References in periodicals archive ?
Her antique chapel-length veil, which had been worn by her grandmother and mother, was ornamented with marcasites and malachites at the crown.
The most interesting Llallagua marcasites are tabular pseudomorphs after pyrrhotite crystals to 20 cm, covered by wavellite, and paper-thin crystals interleaved with equally thin franckeite layers.
In the second stage, pyrrhotite and franckeite were deposited, and in the next stage almost all pyrrhotite was replaced by pyrite, marcasite and siderite.
It also forms masses mixed with marcasite, pyrite and sphalerite.
Enamel buttons were much prized in the 18th century and frequently carried tiny painted scenes of country life set within a gold leaf border, while mother-of-pearl buttons, used for men's waistcoats and knee breeches have a particular fascination since each one was individually fashioned in layers by hand, and occasionally embellished with cut-steel, marcasites, enamel or gold mesh.
If storage is in drawers or closed boxes it's best to keep the marcasites and pyrites segregated.
There once was a man from Dzhezkazgan who bought all the marcasite that cash can.
The worst offenders are marcasite and, to a lesser extent, pyrite, particularly if fine-grained and porous instead of in big lustrous crystals.