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Calcium fluoride · CaF₂ · 4

Fluorite

Fluorite is calcium fluoride, a mineral that grows as glassy cubes and comes in more colours than almost any other: purple, green, blue, yellow, pink and clear, often banded together as "rainbow fluorite". Many pieces glow under ultraviolet light, and the word was coined from its name. It splits cleanly in four directions, so it breaks into neat eight-sided octahedra. It is soft, number 4 on the Mohs scale, so it is a collector's stone more than an everyday ring stone. Clear synthetic fluorite is grown for camera and telescope lenses. Is it valuable? Most fluorite is inexpensive: a pound of rough costs about $15 to $45 on Amazon, and collectors pay more only for sharp, brightly coloured crystals from famous mines.

From the ground to your hand

The same stone at four moments. Tap a photo of a listing to see it on Amazon.

  1. 01 In the ground (step 1 of 4)

    Fluorite cubes from Peyrebrun, France: yellow with purple corners, grown in a mineral vein.

    Fluorite cubes from Peyrebrun, France: yellow with purple corners, grown in a mineral vein.

    Real specimen. Photo: Didier Descouens, CC BY-SA 3.0.

  2. 02 Cleaved (step 2 of 4)

    A green fluorite octahedron. Fluorite splits cleanly in four directions, so rough cubes are tapped into eight-sided shapes like this.

    A green fluorite octahedron. Fluorite splits cleanly in four directions, so rough cubes are tapped into eight-sided shapes like this.

    Amazon listing photo. See it on Amazon

  3. 03 Polished (step 3 of 4)

    A polished fluorite sphere showing the purple and green bands. Fluorite is too soft to facet for wear, so it is mostly polished.

    A polished fluorite sphere showing the purple and green bands. Fluorite is too soft to facet for wear, so it is mostly polished.

    Amazon listing photo. See it on Amazon

  4. 04 Set (step 4 of 4)

    A fluorite heart in sterling silver.

    A fluorite heart in sterling silver.

    Amazon listing photo. See it on Amazon

Mineral
Fluorite (calcium fluoride)
Hardness
4: it defines 4 on the Mohs scale, so it scratches easily
Cleavage
Perfect in four directions, which makes octahedra
Glows under UV?
Often, usually blue; fluorescence is named after it
Main sources
China, Mexico, England, Spain, Morocco and the USA (Illinois)
Purple fluorite cubes with pale barite blades, from Morocco.
Purple fluorite cubes with pale barite blades, from Morocco. Photo: Parent Géry, Public domain.
Fluorite glowing blue under ultraviolet light: the effect named after it.
Fluorite glowing blue under ultraviolet light: the effect named after it. Photo: James St. John, CC BY 2.0.
Pale blue fluorite cubes growing with calcite and scheelite.
Pale blue fluorite cubes growing with calcite and scheelite. Photo: Géry PARENT, CC BY-SA 3.0.

Real fluorite vs the imitations

What real fluorite is and what is sold as fluorite
Natural fluoriteCommon imitations
What it isNatural calcium fluorideGlass, resin, or dyed quartz
ColourPurple, green, blue, yellow; often in bands or zones with sharp edgesEven colour, or swirls that look poured
Shape of roughCubes, or octahedra with flat cleavage facesMoulded or tumbled shapes with no cleavage
Hardness4: a steel knife scratches itGlass and quartz are harder
Under UV lightMany pieces glow blue or violetGlass rarely glows the same way

Real fluorite shows its colour in zones and bands that follow the crystal's shape, with sharp straight boundaries, and rough pieces break along flat, shiny cleavage planes. A cheap UV torch makes many fluorites glow blue. Glass imitations have even colour, tiny round bubbles and no cleavage; a "fluorite" sphere with perfectly regular swirls is worth a second look.

Treatments. Most fluorite is sold untreated. Some soft or cracked material is stabilised with resin before cutting, and a small amount is irradiated or heated to change its colour. Fluorite fades in strong sunlight over time, so keep a specimen out of a sunny window. Do not put it in an ultrasonic cleaner or a hot bath, which can crack it along its cleavage; wipe it with a damp cloth. All gem treatments explained.

Where fluorite comes from

Pins mark mining districts, not exact mines. Drag to move, pinch or scroll to zoom, tap a pin to read about it. Map data © OpenStreetMap contributors.

List of every place on the map (9)
  • Fluorite: Hunan (Xianghualing, Yaogangxian), China. China mines more fluorite than any other country; Hunan mines produce fine purple and green crystals. Position approximate.
  • Fluorite: San Luis Potosí and Coahuila, Mexico. A leading fluorite producer, with purple and pink crystals from mines such as Las Cuevas. Position approximate.
  • Fluorite: Weardale, County Durham, United Kingdom. Green fluorite from the Rogerley mine that glows strongly under UV light.
  • Fluorite: Castleton, Derbyshire, United Kingdom. The only source of Blue John, a banded purple and yellow fluorite.
  • Fluorite: Asturias (Berbes, La Collada), Spain. Purple and yellow fluorite cubes from mines near the coast. Position approximate.
  • Fluorite: Cave-in-Rock district, USA. Once the main US fluorite mines; fluorite is the Illinois state mineral.
  • Fluorite: Elmwood mine, Tennessee, USA. Large purple fluorite cubes with calcite. Position approximate.
  • Fluorite: El Hammam, Morocco. Purple fluorite cubes, often with barite. Position approximate.
  • Fluorite: Peyrebrun, Tarn, France. Yellow and purple fluorite cubes from a former mine. Position approximate.

How it is cut

Fluorite is soft and splits easily, so it is mostly polished into spheres, towers and tumbled stones, or cut as . Faceted fluorite exists, but it is a collector's stone because it needs careful cutting and careful wear. See cuts from easiest to hardest and whether cutting your own is cheaper than buying cut.

What to buy

Checked in stock on October 10, 2026. Photos are the listings' own; prices are rounded.

Amethyst, the other purple crystalClear quartzReading a gem listingGem treatments

Your kit for fluorite

Five tools that let you check what you bought (a loupe, a UV torch, locking tweezers, a gem box and a pocket scale), plus a turntable that spins your stone under the light the way jewellers show one. The full collector's kit.

LookGemOro 10x triplet loupeunder $20LookDARKBEAM filtered 365 nm UV flashlightabout $10HandleHonoson locking tweezers, 3 packabout $10StoreTeensery gem display boxes with clear lids, 10 packabout $9ShowComXim motorized turntable, adjustable speed and directionabout $15MeasureGemOro Platinum XP500 pocket scale, 0.01 gabout $40

In short

Fluorite is a soft, colourful crystal: beautiful on a shelf and under a UV torch, risky on a ring. Buy rough, octahedra or polished pieces, look for colour in sharp bands, and keep it out of the sun and the ultrasonic cleaner.

See our first pick: Zenkeeper rough fluorite, 1 lb, mixed purple and green

Frequently Asked Questions

Is fluorite valuable?

Most fluorite is inexpensive. A pound of rough fluorite costs about $15 to $45 on Amazon, and polished spheres and octahedra are usually under $50. Collectors pay more for sharp, brightly coloured crystals from famous localities, such as green fluorescent fluorite from Weardale in England or Blue John from Castleton.

Is fluorite good for a ring?

Not for everyday wear. At 4 on the Mohs scale, everyday dust (which contains quartz) scratches it, and a knock can split it along its cleavage. It is better as a pendant, earrings or a specimen.

Are fluorite octahedrons natural?

The shape is natural but usually made by hand. Fluorite grows mostly as cubes, but it splits cleanly along four directions, so miners and cutters tap it apart into eight-sided octahedra. Their flat faces are cleavage planes, not crystal faces.

Why does fluorite glow under UV light?

Traces of elements such as europium and yttrium in the crystal absorb ultraviolet light and give off visible light, usually blue. In 1852 the physicist George Stokes named this effect fluorescence after fluorite.

Is fluorite toxic?

Handling it is safe; it is the same calcium fluoride that forms in nature everywhere. Do not grind it and breathe the dust, and do not put it in drinking water.

What is Blue John?

A banded purple and yellow fluorite found only near Castleton in Derbyshire, England, carved into bowls and vases since the 18th century.

Photo credits

  • fluorite-peyrebrun.webp: Didier Descouens, CC BY-SA 3.0, via Wikimedia Commons.
  • fluorite-barite-morocco.webp: Parent Géry, Public domain, via Wikimedia Commons.
  • fluorite-fluorescing.webp: James St. John, CC BY 2.0, via Wikimedia Commons.
  • fluorite-scheelite-calcite.webp: Géry PARENT, CC BY-SA 3.0, via Wikimedia Commons.
  • Product photos: Amazon listings, via the Amazon Product Advertising (Creators) API.

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