triclinic
Plagioclase (Albite Twin)
(Na,Ca)(Al,Si)4O8
Quick Facts
Hardness
6-6.5
Specific Gravity
2.62-2.76
Refractive Index
1.525-1.590
Crystal Structure
triclinic[-1]:{010}@1.0 + {001}@0.8 + {100}@0.5 + {110}@0.4 | twin(albite) triclinic
-1
{010} {001} {100} {110}
Physical Properties
Crystal Systemtriclinic
Hardness (Mohs)6-6.5
Specific Gravity2.62-2.76
CleavagePerfect in two directions at approximately 90 degrees
FractureUneven to conchoidal
LustreVitreous to pearly
Optical Properties
Refractive Index1.525-1.590
Birefringence0.007-0.013
PleochroismNone to weak
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Open in Playground triclinic[-1]:{010}@1.0 + {001}@0.8 + {100}@0.5 + {110}@0.4 | twin(albite) Related Minerals
Other minerals in the triclinic system