Sorosilicates

Sorosilicates

Named after the Dutch Colonel, H. Von Prehn (1733-1785), this mineral was discovered in 1788 in South Africa. It occurs as a secondary mineral lining cavities in basalt and is characterized by its green color and crystalline aggregates forming reniform surfaces.

Discovered in 1853 in Romania, this mineral was named in allusion to the hemimorphic (different at the ends) morphology of the crystals. An ore of zinc, this mineral occurs as a secondary mineral found in the oxidized portion of zinc deposits.

Characterized by its peculiar green color and one perfect cleavage, this mineral was discovered in 1801 in France. It forms during the metamorphism of an impure limestone and is especially characteristic of contact metamorphic deposits in limestone. The name comes from the Greek word meaning "increase," in allusion to the crystal characteristic of one longer side at the base of the prism.

The sorosilicates are characterized by isolated double silicate tetrahedra that share an oxygen, creating an hourglass-like shape. This subclass contains the smallest number of minerals of all the silicate subclasses. All of the minerals in this subclass are rare except for epidote, which is widespread in metamorphic environments.