Axinite


Axinite

Axinite from California
General
Category Mineral
Chemical formula (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 crystals
Crystal system Triclinic
Cleavage Good on {100}
Fracture Conchoidal
Mohs Scale hardness 6.0-7.5
Luster Vitreous
Streak White
Specific gravity 3.18-3.37
Optical properties Biaxial (-)
Refractive index nα = 1.672 - 1.693 nβ = 1.677 - 1.701 nγ = 1.681 - 1.704
Birefringence δ = 0.011
Pleochroism Strong
References [1][2]

Axinite is a brown to violet-brown, or reddish-brown bladed group of minerals composed of calcium aluminium boro-silicate, (Ca,Fe,Mn)3Al2BO3Si4O12OH. Axinite is pyroelectric and piezoelectric.

The axinite group includes:[1]

  • Ferro-axinite, iron rich, lilac brown to black
  • Magnesio-axinite, magnesium rich, pale blue to gray
  • Manganaxinite, manganese rich, yellow-orange
  • Tinzenite, iron - manganese intermediate, yellow

Gallery

Axinite from California

Axinite

Collection of Ferro-axinite at the National Museum of Natural History

References

  1. ^ a b http://mineral.galleries.com/Minerals/Silicate/AXINITE/AXINITE.htm Mineral Galleries
  2. ^ http://www.mindat.org/min-440.html Mindat
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