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PYRRHOTITE

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Originally appearing in Volume V22, Page 697 of the 1911 Encyclopedia Britannica.
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PYRRHOTITE , a See also:

mineral See also:species consisting of See also:iron sulphide and crystallizing in the hexagonal See also:system. The See also:formula is Fen, Sn.+, where n may vary from 5 to 16; usually it is See also:Fez Sa or See also:Fell S,2, the latter being also the See also:composition of the artificially prepared See also:compound. Small amounts of See also:nickel and See also:cobalt are often See also:present. Crystals have the See also:form of hexagonal plates bounded at their edges by faces cf a hexagonal See also:prism and pyramids, which are deeply striated horizontally. More frequently, however, the mineral is massive, with a laminar or granular structure. The See also:colour is See also:bronze-yellow and the lustre metallic; the streak is greyish-See also:black. The hardness is 4 and the specific gravity 4 58–4.64. The mineral is magnetic, sometimes with See also:polarity, and it is therefore often called " magnetic See also:pyrites." Pyrrhotite occurs in metalliferous See also:veins, and as grains and plates disseminated through various rocks. In the gabbros and norites of See also:Norway and See also:Sweden it has been concentrated by magmatic differentiation at the margins of the igneous masses. Large bodies of massive pyrrhotite occur at Bodenmais in See also:Bavaria and in Wheal Jane near See also:Truro in See also:Cornwall. Crystallized specimens are from the metalliferous veins at Morro Velho in See also:Brazil, See also:Kongsberg in Norway, and Andreasberg in the Harz. Crystals of pyrrhotite have also been observed in meteoric stones; but iron sulphide appears more commonly in meteorites, especially in meteoric irons, as troilite (FeS), which, if really distinct from pyrrhotite, has not been met with in terrestrial rocks.

(L. J.

End of Article: PYRRHOTITE

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