Mineral Species: Sphalerite

Chemical Formula: ZnS

Chemical Name: Zinc Sulfide

Mineral Class: Sulfide

Mineral Notes: Sphalerite is a common sulfide and an important ore of Zinc. It is often called Zincblende or Black Jack. The mineral most commonly occurs in hydrothermal veins in all types of rock, especially with other sulfides, like Galena. Nearly all Sphalerite contains some Iron in solid solution, which affects its appearance and properties. Identification is made on the basis of its perfect cleavage and resinous luster.

Description: Several, very lustrous, black crystals of Sphalerite on limestone matrix. The largest crystal is a complex composite formed from several twinned crystals. It is large and very rare. A superb display specimen showing of the mineral and its complex form extremely well.

Location: Smallcleugh Mine, Nenthead, Cumbria, England.