Judging quality
Look for glassy lustre, sharp cube edges and strong color zoning. Many fluorites fluoresce blue under UV — the phenomenon is named after the mineral. Cleaved octahedra are shaped by hand, not grown.
Halide
Fluorite
The most colorful mineral in the world, fluorite grows in perfect cubes and octahedra, often color-zoned in bands of green, purple and clear within a single crystal.
Care
Soft, with perfect cleavage in four directions. Chips easily; keep out of sunlight, which fades some purple material.
History & lore
Blue John fluorite from Castleton, Derbyshire has been carved into vases since the eighteenth century and is found nowhere else.
Cultural history, recorded as tradition rather than as medical or scientific claim.
Common questions about Fluorite
- What is Fluorite?
- The most colorful mineral in the world, fluorite grows in perfect cubes and octahedra, often color-zoned in bands of green, purple and clear within a single crystal.
- How hard is Fluorite and what is it made of?
- Fluorite is a Halide-family mineral with the composition CaF2. It crystallizes in the isometric system and rates 4 on the Mohs hardness scale. It occurs in green, purple, blue, yellow.
- Where does Fluorite come from?
- Notable localities for Fluorite include China, England (Derbyshire), Mexico, Namibia.
- How do you tell good Fluorite from filler?
- Look for glassy lustre, sharp cube edges and strong color zoning. Many fluorites fluoresce blue under UV — the phenomenon is named after the mineral. Cleaved octahedra are shaped by hand, not grown.
- How do you care for Fluorite?
- Soft, with perfect cleavage in four directions. Chips easily; keep out of sunlight, which fades some purple material.
See it in person
Photographs only go so far
Both rooms are open six days a week, and there is always someone happy to pull pieces out of the case so you can compare them under the light.