Fluorite

Fluorite is a mineral with a wide variety of brilliant colours, ranging from intense purple, blue, green or yellow; also colourless, reddish orange, pink, white and brown. A single crystal can be multi-coloured. This mesmerising mineral is well known and prized for its glassy lustre and rich variety of colours. The most common and popular colour is purple, very similar shade to amethyst. These colours can also be sourced in a variety of hues too, giving fluorite the reputation as the most colourful mineral in the world.

The blue, green and yellow varieties are also deeply coloured, popular and attractive. The colourless variety is not as well received as the coloured varieties, but their rarity still makes them sought after by collectors. A brown variety found in Ohio and elsewhere has a distinctive iridescence that improves an otherwise poor colour for fluorite. The rarer colours of pink, reddish orange (rose) and even black are usually very attractive and in demand.

Most specimens of fluorite have a single colour. One crystal could potentially have four or five different zones or bands. The typical habit though,  is a cube and the zones are often in cubic arrangement.

The origin of the word comes from the use of fluorite as a flux in steel and aluminium processing. It was originally referred to as fluorospar by miners and is still called that today. Fluorite is also used as a source of fluorine for hydrofluoric acid and fluorinated water. Other uses of fluorite include an uncommon use as a gemstone (low hardness and good cleavage reduce its desirability as a gemstone), ornamental carvings (sometimes misleadingly called Green Quartz) and special optical uses.

The Famous Blue John

One of the oldest and most famous deposits of fluorite in the world is the Blue John Cavern in Derbyshire, England, which produces a purplish-blue. The name comes from the French bleu et jaune, which translates to ‘blue and yellow,’ named due to its colour characteristic – yellow banding among the purplish-blue. While the English mines are nearly depleted, fluorite resembling the classic Blue John fluorite has been found recently in China, and are very popular among collectors.