Chemical symbol: ZnS and (Zn, Fe)S
It consists largely of zinc sulfide in crystalline form but almost always contains variable iron. When iron content is high it is an opaque black variety, marmatite. It is usually found in association with galena, pyrite, and other sulfides along with calcite, dolomite, and fluorite. Miners have also been known to refer to sphalerite as zinc blende, black-jack, and ruby jack.
Crystal System: Isometric
Hardness: 3 1/2 to 4
Color: brown, yellow, green, black, red
Streak: brownish white to pale yellow
Mineral of the Month: October 2014
It is found in the USA; Tennessee, Colorado, Kansas, Oklahoma, Alaska, Idaho
It has been found worldwide but the more notable locations are in Europe, specifically the Baltic area, Mexico, Peru, Canada, England and Russia.
Besides being the chief ore of zinc, sphalerite is also the chief ore of gallium, indium and cadmium. As such, it becomes a way for miners to locate those metals. It can be altered to create hemimorphite, smithsonite and willemite. It has also been used to make a beautiful gemstone in its own right, for collectors only. Though it can resemble a colored diamond, sphalerite is often considered too soft to be set. When it becomes an aggregate with wurtzite and galena, it is called Schalenblende and is polished as an ornamental stone.
Before being called sphalerite, it was called blende. This comes from a German word meaning “blind” or “deceptive.” This is because it resembles galena and would fool miners into mining it for lead that wasn’t there. Sphalerite comes from a Greek word meaning treacherous rock; it is treacherous in the sense that is it easily misidentified because of its color. In modern times, the black sphalerite crystal has been nicknamed Black Jack and the red crystal has been nicknamed Ruby Jack.
This is a very aesthetic mass of reddish-brown sphalerite crystals with large, thick crystals. Joplin, Jasper Co. Missouri
Sphalerite crystal cluster
Tetrahedral sphalerite crystals
Sphalerite on dolomite from the Tri-State District, Jasper County, Missouri, USA
Gem quality twinned cherry-red sphalerite crystal (1.8 cm) from Hunan Province, China
Faceted stones of sphalerite