Home > Pyrrhotite
Pyrrhotite is an unusual iron sulfide mineral with a variable iron content: Fe(1-x)S (x = 0 to 0.2). The FeS endmember is known as troilite. Also called magnetic pyriteThe mineral pyrite or iron pyrite is iron disulfide, FeS. It has isometric crystals that usually appear as cubes or pyritohedrons. It has a slightly uneven and conchoidal fracture, a hardness of 6-6. 5, and a specific gravity of 4. Its metallic luster and because the color is similar to pyrite and it is weakly magnetic, the magnetismIn physics, magnetism is a phenomenon by which materials exert an attractive or repulsive force on other materials. Some well known materials that exhibit easily detectable magnetic properties are iron, some steels, and the mineral lodestone; however, all increases as the iron content decreases.
Pyrrhotite is odd also because it has two crystal symmetries. When pyrrhotite is high in iron and the formula is closer to true FeS the structure is hexagonal. But, when it is low in iron, the structure is monoclinic. Both symmetries occur together is the same specimen.
The name is derived from Greek pyrrhos, flame-colored.
Pyrrhotite is a rather common trace constituent of igneous rocks. It occurrs as segregation deposits from maficMafic is a term used in geology for silicate minerals, magmas, volcanic, and intrusive igneous rocks that have relatively high concentrations of the heavier elements. The term is a combination of " magnesium" and ferric the Latin word for iron(III), but m igneous rocks associated with pentlanditePentlandite is a iron- nickel sulfide, (Fe,Ni)S. Pentlandite usually has a Ni:Fe ratio of close to 1:1. It also contains minor cobalt. Pentlandite forms isometric crystals, but is normally found in massive granular aggregates. It is brittle with a hardnes, chalcopyrite and other sulfides. It also occurrs in pegmatites and in contact metamorphic zones. The troilite endmember is found in meteorites.
References and external links
Minerals
Sulfide minerals
