triclinic Tectosilicates
Amazonite
KAlSi3O8
Crystal Structure
#! Species: Amazonite (Microcline Feldspar)
#! System: Triclinic (-1)
#! Habit: Prismatic with Baveno twinning and lead-green colour
triclinic[-1]:{010}@1.0 + {001}@0.9 + {110}@0.7[colour:green] | twin(baveno)
triclinic
-1
{010} {001} {110}
Quick Facts
Hardness
6.0
Specific Gravity
2.56
Refractive Index
1.522
Optical Character
Biaxial -
Physical Properties
Crystal Systemtriclinic
Hardness (Mohs)6.0
Specific Gravity2.56
CleavagePerfect {001} and {010} at approximately 90 degrees
FractureUneven
LustreVitreous
Optical Properties
Refractive Index1.522
Birefringence0.008
Optical CharacterBiaxial -
Dispersion0.012
PleochroismNone
Colours
GreenBlue-greenTurquoise blueWith white streaks (perthite)
Localities
Colorado (USA - Pikes Peak, Crystal Peak)BrazilRussia (Kola Peninsula, Urals)MadagascarIndiaNamibia
Crystal Forms
pinacoidprismBaveno twins (common)
Notes
Color from Pb+H2O color centers, not copper; often perthitic with white albite streaks
Related Minerals
Other minerals in the triclinic system
