Apatite
Apatite is the collective name for a group of calcium phosphate minerals, chiefly hydroxylapatite, fluorapatite, and chlorapatite, sharing the general formula Ca5(PO4)3(F,Cl,OH). It is the mineral that defines hardness 5 on the Mohs scale and forms the mineral component of bones and teeth in vertebrates. Gem-quality crystals range from pale green and blue to vivid neon blue-green varieties prized by collectors.
Apatite properties at a glance
| Type | Minerals |
|---|---|
| Chemical formula | Ca5(PO4)3(F,Cl,OH) |
| Mohs hardness | 5 |
| Crystal system | Hexagonal |
| Luster | Vitreous to subresinous |
| Streak | White |
| Cleavage | Poor, basal and prismatic |
| Fracture | Conchoidal to uneven |
| Specific gravity | 3.1–3.2 |
| Transparency | Transparent to translucent |
| Common colors | Green, Blue, Yellow, Violet, Colorless, Brown |
| Rarity | common |
Geology & background
Apatite crystallizes in a wide range of igneous, metamorphic, and sedimentary settings, appearing as an accessory mineral in granites and pegmatites, in metamorphosed limestones, and as massive phosphate rock in sedimentary basins built from ancient marine bone and guano deposits. Well-formed hexagonal crystals come from pegmatites in Brazil, Myanmar, and Madagascar, while the intense neon blue-green material that has become highly sought after originates mainly from Madagascar's Ambatondrazaka region.
Rockhounds should know that gem apatite is notably soft and brittle for a faceted stone, so pieces destined for rings need protective settings and careful handling. Massive apatite forms the basis of phosphate rock mined for fertilizer, making this mineral group economically important far beyond the collector market. Because apatite occurs in so many colors and habits, confirming an identification with a hardness test is often more reliable than trusting color alone.
How to identify Apatite
Apatite typically forms hexagonal prisms with flat terminations, though it also occurs massive or granular. Color spans colorless, green, blue, yellow, violet, and brown, with a vitreous to slightly resinous luster and a white streak. Its defining trait is a hardness of exactly 5, scratched easily by a steel knife blade yet resistant to a fingernail. Cleavage is poor and fracture is conchoidal to uneven. Apatite is frequently mistaken for beryl, tourmaline, or fluorite until a hardness test settles the question.
- Compare the specimen's color, luster, crystal habit, grain size, streak, and locality before confirming.
- Use multiple photos when possible, including a fresh surface and a close view of texture.
Where Apatite is found
Reported from multiple localities worldwide; verify locality against specimen provenance when available.
How much is Apatite worth?
| Entry-level specimen | $2 |
|---|---|
| Typical collector specimen | $20 |
| Premium specimen | $150+ |
Value depends on size, crystal quality, color, locality, rarity, damage, and provenance.
Common uses
- Collector specimens
- Education
- Field identification
- Industrial or lapidary use when suitable
Interesting facts
- Apatite is the reference mineral that anchors hardness 5 on Friedrich Mohs's original 1812 scratch-hardness scale.
- The phosphate mineral in human bones and tooth enamel is a biological form of apatite called hydroxylapatite.
- Madagascar's neon blue-green apatite gets its striking color from trace amounts of manganese and vanadium.
Care & safety
Handle as a collector specimen until hardness, cleavage, and fracture are verified.
Avoid inhaling dust. Do not cut, grind, or polish unknown specimens without eye protection and a proper respirator.
.jpg?width=320)
.jpg?width=320)