Axinite

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Axinite
Category Mineral
Chemical formula calcium aluminum boro-silicate, (Ca,Fe,Mn)3Al2BO3Si4O12OH or Ca2(Fe,Mn)Al2BSi4O15(OH)
Identification
Color Reddish brown to yellow to colorless. Blue, violet, grey.
Crystal habit Tabular, wedge shaped crystal
Crystal system Triclinic
Cleavage Good
Fracture Conchoidal
Mohs Scale hardness 6.5-7
Luster Vitreous
Refractive index 1.68-1.723
Pleochroism Strong
Streak White
Specific gravity 3.26-3.41

Axinite is a brown to violet-brown, or reddish-brown bladed mineral composed of calcium aluminum boro-silicate, (Ca,Fe,Mn)3Al2BO3Si4O12OH. Axinite is pyroelectric and piezoelectric. http://www.earthquestminerals.com/ax1%20lrg.htm