Apatite vs Biotite
| Property | Apatite | Biotite |
|---|---|---|
| Formula | Ca5(PO4)3(F,Cl,OH) | K(Mg,Fe)3(AlSi3O10)(OH)2 |
| Crystal System | Hexagonal | Monoclinic |
| Mineral Class | 08 Phosphates, Arsenates, and Vanadates | 09 Silicates |
| Mohs Hardness | 5.0 | 2.5-3.0 |
| Color | Green, blue, yellow, violet, colorless | Black, dark brown, dark green |
| Luster | Vitreous | Vitreous |
| Streak | White | White to gray |
| Transparency | Transparent | Translucent |
| Cleavage | Poor {0001} | Perfect basal {001} |
| Fracture | Conchoidal to uneven | Uneven |