Fluorite

Fluorite is one of the most colourful minerals, sometimes showing bands of purple, green, blue and yellow within a single crystal. It is also fragile, and it has two distinctions in science: it is the mineral that gave us the word fluorescence, and its crystals often form perfect cubes and octahedra.

What it is

Fluorite is calcium fluoride, with a hardness of 4 on the Mohs scale, which makes it much softer than quartz. It has perfect cleavage in four directions, so it splits into neat octahedra if struck, and this is why it is easily damaged. It forms in veins of hot water, often alongside metal ores, and is found in China, Mexico, England, Namibia, Morocco and the United States, among many other countries.

Some fluorite glows under ultraviolet light, which is the effect called fluorescence, after the mineral. The name comes from the Latin fluere, to flow, because fluorite was used as a flux in smelting metal.

History and culture

In England, a banded purple and yellow variety called Blue John is mined in a few caverns near Castleton in Derbyshire, and it has been turned into vases and ornaments since the eighteenth century. The source is very limited, which makes Blue John pieces collectable, and the caves are open to visitors.

Fluorite has been carved since antiquity. Some scholars have suggested that the mysterious murrhine vessels prized in ancient Rome were carved from fluorite, although this is debated and not settled. The mineral was a minor industrial material for centuries and is now used in steelmaking, chemical manufacture and optics.

What crystal traditions associate with it

In many crystal traditions, fluorite is associated with focus, order and mental clarity, which some people connect to its regular crystal shapes. It is often linked with the third eye and with Pisces and Capricorn in zodiac lists, though sources vary. These are symbolic associations, not claims about effects.

How people use it

Fluorite is prized as a display stone, in the form of cubes, octahedra, clusters and carved spheres. It is sometimes made into beads and pendants, though it does not wear well. People keep fluorite on a desk as an object of attention, or hold a polished piece during quiet time.

Care and safety

• Fluorite is soft and easily scratched. Keep it away from harder stones and do not wear it in rings that take knocks.
• Avoid heat, strong sunlight, and sudden temperature changes, which can crack or fade the colour.
• Do not soak it or use harsh cleaners, steam or ultrasonic cleaning. A soft dry or barely damp cloth is best.
• Acids attack fluorite.
• Do not swallow fluorite or place it in drinking water, and do not make an elixir with it.
• Keep pieces away from children and pets.

Sourcing

Fluorite is mined both for industry and for collectors, with China a dominant producer. Some mining has environmental and labour issues, and the supply of Blue John in England is very limited. Ask where a piece came from, and be aware that dyed or man-made stones are also sold.

A note on health. Crystals are valued for beauty, meaning and ritual. There is no scientific evidence that they treat health conditions. If you are struggling with your health or mood, please speak to a doctor.

Frequently asked questions