Physical Properties |
|
| Chemical formula | Ca5(PO4)3(OH,F,Cl) |
| Class | Phosphate |
| Crystal system | Hexagonal |
| Habit | Typically prismatic Colloform Massive Granular |
| Color | Green Yellow Variable |
| Hardness | 5 |
| Specific gravity | 3.2 |
| Cleavage | Good (001), poor {100} |
| Fracture | Conchoidal |
| Luster | Subresinous |
| Transparency | Transparent to translucent |
| Streak | White |
Optical Properties |
|
| PPL | Colorless Nonpleochroic |
| XPL | 1st order gray Often plucked; you may see a small prismatic hole indicative of apatite |
| δ | 0.003 |
| after Perkins, 400 |
Apatite in Hand Sample
Three subhedral apatite crystals
Apatite (green) in orthoclase
Greenish apatite in slabbed nelsonite
Greenish apatite in uncut nelsonite
Apatite in Thin Section
Apatite is obnoxious in thin section. It often plucks out in grinding, leaving a little hexagonal “apatite wuz here” hole in your section. That’s why there’s nothing here yet. We’re working on it.