Mineral Species: Pyrrhotite
Chemical Formula: FeS
Chemical Name: Iron Sulfide
Mineral Class: Sulfide
Mineral Notes: Pyrrhotite is an unusual mineral with some fascinating properties. First, it has an unusual composition. The amount of Sulphur varies widely, by anything between 20% or 50%. Thus the correct formula is Fe1-xS. Secondly it has two crystal symmetries. When low in Sulphur the structure is hexagonal. When high, it is monoclinic. Usually such differences would result in classification as two separate minerals. However single Pyrrhotite crystals can contain both phases. And finally the mineral is one of the few that are magenetic.
Description: A small quartzite matrix surrounded by several excellently formed crystals of Pyrrhotite. All have stepped faces and surface striations. The colour is coppery-grey with distinct brassy overtones. The luster is very metallic reflecting the high iron content. A good opportunity to acquire a very attractive specimen of an unusual mineral.
Location: Nikolevsky Mine, Dalnegorsk, Russia.
