trigonal
Tourmaline
Complex borosilicate
Quick Facts
Hardness
7-7.5
Specific Gravity
3.01-3.11
Refractive Index
1.620-1.640
Crystal Structure
trigonal[32]:{10-10}@1.0 + {10-11}@0.8 | elongate(c:2.5) trigonal
32
{10-10} {10-11}
Physical Properties
Crystal Systemtrigonal
Hardness (Mohs)7-7.5
Specific Gravity3.01-3.11
CleavageIndistinct
FractureUneven to conchoidal
LustreVitreous
Optical Properties
Refractive Index1.620-1.640
Birefringence0.018
PleochroismStrong (often dark to light of same hue)
Dispersion0.017
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Open in Playground trigonal[32]:{10-10}@1.0 + {10-11}@0.8 | elongate(c:2.5) Related Minerals
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