Phlogopite
| Phlogopite | |
|---|---|
| Missing image Phlogopite.jpg A phlogopite crumbled cleavage plate A phlogopite crumbled cleavage plate | |
| General | |
| Category | Mineral |
| Chemical formula | K(Mg,Fe,Mn)3Si3AlO10(F,OH)2) |
| Identification | |
| Colour | Yellowish- or greenish-brown |
| Crystal habit | Tabular, scaly masses, often small flakes in acid igneous rocks. |
| Crystal system | Monoclinic |
| Cleavage | Basal |
| Fracture | Bends without breaking |
| Mohs Scale hardness | 3 |
| Luster | Pearly, sometimes slightly metallic |
| Refractive index | Trasparent |
| Pleochroism | None |
| Streak | Colorless |
| Major varieties | |
| None | |
Phlogopite is a yellow, greenish or reddish brown member of the mica family of phyllosilicates. It is also known as magnesium mica. Phlogopite is the magnesium endmember of the biotite solid solution series. It occurs in contact metamorphic zones around intrusives into magnesium rich limestones, dolostone, and in some ultramafic igneous rocks.