Talc
Chemical Formula	Mg3Si4O10(OH)2
Species	Silicates
Crystal System	Triclinic
Mohs Scale	1
Specific Gravity	2.58-2.83
Color	Light to dark green, brown, white
Streak	White to pearl green
Luster	Sub-Vitreous, Resinous, Waxy, Greasy, Pearly
Refractive Index	n = 1.538 - 1.550 n = 1.589 - 1.594 n = 1.589 - 1.600
Diaphaneity	Transparent, Translucent
Cleavage	Perfecton
Fracture	Fibrous, Micaceous
Crystal Habit：Foliated to fibrous masses, rare as platey to pyramidal crystals
Geological Setting：Schists and steatite through hydrothermal alteration of mafic rocks. Low temperature metamorphism of siliceous dolomites.