Phyllosilicate - Monoclinic - not a Mica group member but is a member of the Talc series. Talc is found as tabular crystals {001}. foliated and stellate masses, inelastic laminae, less abundant than Talc. Forms from the alteration of Feldspars, in Al-rich rocks, under acidic conditions >300 d C...below which Kaolinite forms.
Pyrophyllite
Formula
Al2Si4O10(OH)2
Crystal System
Triclinic
Crystal Habit
Earthy
Cleavage
Perfect, None, None
Luster
Pearly
Color
brown green, brownish yellow, greenish, gray green, gray white