Fluorite

Fluorite is a mineral with a wide variety of brilliant colours, ranging from intense purple, blue, green or yellow; also colorless, reddish orange, pink, white and brown. A single crystal can be multi-colored. Fluorite is well known and prized for its glassy luster and rich variety of colors. The most common and popular color is purple, very similar shade to amethyst. These colours can also be sourced in a variety of hues between each of the previously mentioned colors are also possible. Giving fluorite the reputation as the most colorful mineral in the world.

The blue, green and yellow varieties of fluorite are also deeply colored, popular and attractive. The colorless variety is not as well received as the colored 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 color for fluorite. The rarer colors of pink, reddish orange (rose) and even black are usually very attractive and in demand.

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

The origin of the word fluorite comes from the use of fluorite as a flux in steel and aluminum 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. The element fluorine also gets its name from fluorite, fluorines only common mineral. 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.
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 fluorite known as Blue John.

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 other banded fluorites, like the one above, are very popular among collectors.