triclinic
Sunstone
(Na,Ca)(Al,Si)4O8
Quick Facts
Hardness
6.0
Specific Gravity
2.62
Refractive Index
1.537
Crystal Structure
triclinic[-1]:{010}@1.0 + {100}@0.9 + {001}@0.7 + {110}@0.5 triclinic
-1
{010} {100} {001} {110}
Physical Properties
Crystal Systemtriclinic
Hardness (Mohs)6.0
Specific Gravity2.62
CleavagePerfect in two directions at ~90 degrees
FractureUneven to conchoidal
LustreVitreous
Optical Properties
Refractive Index1.537
Birefringence0.007-0.010
PleochroismModerate in coloured Oregon material (red to green dichroism)
Dispersion0.012
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