Apatite
JewelryWiki Editorial·3 sources·Reviewed 2026-08-04
Defines point 5 on the Mohs scale itself. Attractive but too soft for rings in regular wear.
Properties
| Property | Value | Authority |
|---|---|---|
| Mohs hardness | 5 [3] | — |
| Refractive index | 1.628–1.649 [1] | — |
| Specific gravity | 3.16–3.23 [1] | — |
| Chemical formula | Ca5(PO4)3F Apatite is a GROUP. This is fluorapatite, its commonest member and the one usually cut as a gem; hydroxylapatite and chlorapatite substitute OH or Cl for the F and are different minerals. [3] | — |
| Crystal system | Hexagonal [2] | — |
Sources
- International Gem Society — reference charts (Mohs hardness, specific gravity, refractive index) — International Gem Society (IGS reference charts)
- Wikipedia — mineral article infoboxes (crystal system) — Wikipedia contributors (Wikipedia mineral infoboxes)
- Handbook of Mineralogy — Mineral Data Publishing / Mineralogical Society of America (Handbook of Mineralogy, Mineral Data Publishing)