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trigonal
Corundum (Barrel)
Al2O3
Quick Facts
Hardness
9.0
Specific Gravity
3.99
Refractive Index
1.762
Crystal Structure
trigonal[-3m]:{10-11}@1.2 + {10-10}@0.6 + {0001}@0.2 | elongate(c:1.2) trigonal
-3m
{10-11} {10-10} {0001}
Physical Properties
Crystal Systemtrigonal
Hardness (Mohs)9.0
Specific Gravity3.99
CleavageNone (parting on twin planes)
FractureConchoidal to uneven
LustreVitreous to adamantine
Optical Properties
Refractive Index1.762
Birefringence0.008
PleochroismDistinct to strong (depends on colour)
Dispersion0.018
Interactive Preview
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Open in Playground trigonal[-3m]:{10-11}@1.2 + {10-10}@0.6 + {0001}@0.2 | elongate(c:1.2) Related Minerals
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