Apatite Physical Properties

Apatite Physical Properties

* Apatite Chemical composition: Ca5(PO4)3(F,Cl,OH)
* Class: phosphate
* Crystal system: hexagonal; 6/m
* Crystal habit: commonly as prismatic crystals terminated by first order pyramids often with basal planes. Also can be in massive granular to compact masses.
* Twinning: twins are rare
* Specific gravity: 3.15 - 3.20
* Index of refraction: 1.63 - 1.64
* Birefringence: weak to moderate (0.001-0.015)
* Pleochroism: weak to moderate
* Hardness: 5
* Color: usually in shades of yellow, green or brown, more rarely colorless, violet or blue.
* Luster: vitreous to sub-resinous, occaisionally a chatoyant effect is visible.
* Transparency: transparent to opaque
* Cleavage:poor on {0001}
* Fracture: uneven, brittle
* Streak: white to yellow-gray