Identification guide · Minerals
How to Identify Fluorite
Fluorite is usually purple, green, and blue with a vitreous luster and is transparent. It has a Mohs hardness of 4. A steel knife blade (Mohs 5.5) scratches it; a copper coin does not. Its streak is white. It is most often confused with Calcite, Analcime, and Anhydrite; the tests below separate them.
Fluorite identification checklist
| Color | Purple, Green, Blue, Yellow, Colorless, Pink | Look at a clean, dry surface in daylight. Color zoning, banding or spots are as diagnostic as the hue. |
|---|---|---|
| Luster | Vitreous | Fresh surfaces shine like glass; a dull surface usually means weathering, so chip or wet a corner. |
| Transparency | Transparent | Hold a thin edge up to a bright light and note whether light passes through. |
| Mohs hardness | 4 | A steel knife blade (Mohs 5.5) scratches it; a copper coin does not. |
| Streak | White | Drag a corner across unglazed porcelain (the back of a bathroom tile) and check the powder color. |
| Cleavage | Perfect octahedral | |
| Fracture | Flat | |
| Specific gravity | 3.2 | Heavier than it looks (specific gravity about 3.2). |
| Crystal system | Cubic |
Fluorite look-alikes and how to tell them apart
Fluorite is harder (Mohs 4) than Calcite (Mohs 3), so Fluorite will scratch Calcite and not the other way round. A copper coin (Mohs 3.5) scratches it, but a fingernail does not. Fluorite vs Calcite →
Analcime is harder (Mohs 5–5.5) than Fluorite (Mohs 4), so Analcime will scratch Fluorite and not the other way round. A steel knife blade (Mohs 5.5) scratches it; a copper coin does not. Fluorite vs Analcime →
Both sit near Mohs 4, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Fluorite vs Anhydrite →
Apatite is harder (Mohs 5) than Fluorite (Mohs 4), so Apatite will scratch Fluorite and not the other way round. A steel knife blade (Mohs 5.5) scratches it; a copper coin does not. Fluorite vs Apatite →
Field tips
- Check whether the specimen's color and texture match typical Fluorite examples.
- Use hardness, streak, luster, grain size, and locality together; no single trait is enough for every specimen.
Fluorite identification FAQ
How can you tell if a rock is Fluorite?
Check the color (purple, green, blue, and yellow), the vitreous luster, a Mohs hardness of 4 and a white streak. Photographing it with the StoneSnap app gives a match in seconds.
What is the hardness of Fluorite?
Fluorite has a Mohs hardness of 4. A steel knife blade (Mohs 5.5) scratches it; a copper coin does not.
What is the difference between Fluorite and Calcite?
Fluorite (Mohs 4, vitreous luster) and Calcite (Mohs 3, vitreous luster) look alike, but hardness, streak and heft usually separate them. See the full Fluorite vs Calcite comparison for a side-by-side table.
Is Fluorite worth anything?
Entry-level Fluorite specimens sell for around $5, typical collector pieces about $25, and premium examples $200 or more depending on size, quality and locality.
What color is Fluorite?
Fluorite is most often purple, green, blue, and yellow. Color varies with impurities and locality, so confirm with hardness and luster rather than color alone.
