Phlogopite

Phlogopite
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.

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