Chalcopyrite-pyrrhotite-magnetite from the Precambrian of Ontario, Canada. (~3.5 centimeters across along the base) Dull brassy & brownish-brassy area at ce — Photo: James St. John · CC BY 2.0
Pyrrhotite
Also known as: Magnetic pyrites.
The iron-deficient iron sulfide — 'flame-colored' — a weakly magnetic mineral common in nickel deposits.
Intro adapted from Wikipedia (CC BY-SA).
Pyrrhotite is an IMA-recognized mineral species in the sulfide class, with the chemical formula Fe₇S₈.
It crystallizes in the monoclinic crystal system (space group P6_3/mmc). It is a member of the Nickeline structural group.
Key properties: Mohs hardness 3.5–4.5; specific gravity 4.58–4.65; typically brown or gray; Dark grayish black streak; Metallic luster.
IMA symbol Pyh, grandfathered status — known before the IMA’s founding, named in 1835.
Mainly in mafic igneous rocks, typically as magmatic segregations; also in pegmatites, and in high-temperature hydrothermal and replacement veins, and in sedimentary and metamorphic rocks; in iron meteorites.
It is found associated with Pyrite, marcasite, chalcopyrite, pentlandite, many other sulfides, magnetite, calcite, dolomite.
Its name comes from the Greek for redness, in allusion to its color.
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