ගිනිබොකු තෝර
Andalusite
General
CategoryNesosilicates
රසායනික සූත්‍රයAl2SiO5
Strunz classification09.AF.10
Crystal symmetry2/m 2/m 2/m - Dipyramidal
Unit cella = 7.7980 Å b = 7.9031 Å c = 5.5566 Å; Z = 4
Identification
පාට / පැහැයPink, violet, yellow, green, white, gray; in thin section, colorless to pink or green
Crystal habitAs euhedral crystals or columnar aggregates having nearly square cross sections; fibrous compact to massive
Crystal systemorthorhombic
TwinningOn {101}, rare
CleavageGood on {110}, poor on {100}
Fractureuneven to subconchoidal
Mohs scale hardness6.5 - 7.5
LusterVitreous
StreakWhite
DiaphaneityTransparent to nearly opaque with inclusions
Specific gravity3.17 (+/- .04)
Optical propertiesdouble refractive, biaxial negative; chiastolite has anomalous aggregate reaction.[1]
Refractive indexnα = 1.629 - 1.640 nβ = 1.633 - 1.644 nγ = 1.638 - 1.650
Birefringenceδ = 0.009 - 0.010
PleochroismWeak
2V angle71 - 86°
Dispersionr < v strong
Ultraviolet fluorescencenon-fluorescent
References[1][2][3][4]
  1. ^ a b Gemological Institute of America, GIA Gem Reference Guide 1995, ISBN 0-87311-019-6
  2. ^ http://rruff.geo.arizona.edu/doclib/hom/andalusite.pdf Handbook of Mineralogy
  3. ^ http://www.mindat.org/show.php?id=217&ld=1&pho= Mindat.org
  4. ^ http://webmineral.com/data/Andalusite.shtml Webmineral data
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