Description

SPHALERITE SPECIMEN

Some information about sphalerite:

Sphalerite ((Zn, Fe)S) is a mineral that is the chief ore of zinc. 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.

Its color is usually yellow, brown, or gray to gray-black, and it may be shiny or dull. Its luster is adamantine, resinous to submetallic for high iron varieties. It has a yellow or light brown streak, a Mohs hardness of 3.5–4, and a specific gravity of 3.9–4.1. Some specimens have a red iridescence within the gray-black crystals; these are called “ruby sphalerite”. The pale yellow and red varieties have very little iron and are translucent. The darker, more opaque varieties contain more iron.

Sphalerite is the most important ore of zinc. Around 95 % of all primary zinc is extracted from sphaleritic ores. However, due to its variable trace element content, sphalerite is also an important source of many minor metals, such as cadmium, gallium, germanium and indium.