Goshenite

Goshenite is the colourless variety of beryl — beryl with none of the trace elements that colour its better-known relatives. It is named after Goshen, Massachusetts, where it was first described. Being pure beryl, it is sometimes used as a stand-in to demonstrate the species' clarity and brilliance.

Properties

Goshenite is hexagonal, hard (7.5–8) and forms clean prismatic crystals. Because it lacks the chromium, iron or manganese that produce green, blue and pink beryls, it is water-clear; historically it was even used for spectacle and instrument lenses.

Occurrence

It forms in granitic pegmatites worldwide, including Brazil, Pakistan, Russia and the United States. Coloured members of the family include emerald, aquamarine, morganite and heliodor.