Sphalerite or Blende

Sphalerite commonly occurs as crystals of tetrahedral or rhombododecahedral shape, sometimes very complex, with striated and curved faces. Less frequent are the cases in which it is found in the form of compact, granular, fibrous or botryoidal masses. The colour shades of this mineral range from colourless to black, with intermediate tints ranging from brown to yellow, red and green. Depending on its composition it can be transparent, translucent or opaque. Sphalerite is heavy, hard, brittle, not fusible when pure and soluble in hydrochloric acid.

It frequently forms in hydrothermal veins, in association with galena, pyrite, baryte and fluorite, but also within metamorphic and sedimentary deposits.

The primary use of this mineral is the extraction of zinc and, less frequently, of cadmium, gallium and indium.