trigonal
Corundum (Barrel)
Al2O3
Quick Facts
Hardness
9
Specific Gravity
3.99-4.01
Refractive Index
1.762-1.770
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
Specific Gravity3.99-4.01
CleavageNone (parting on twin planes)
FractureConchoidal to uneven
LustreVitreous to adamantine
Optical Properties
Refractive Index1.762-1.770
Birefringence0.008
PleochroismDistinct to strong
Dispersion0.018
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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
Other minerals in the trigonal system