CHEMICAL COMPOSITION:
Andalusite gemology
Species: Andalusite
Color: Yellow-green, green, brownish-red, reddish brown
Chemical composition: AI2,SiO5, aluminum silicate
Crystal system: (Orthorhombic), thick columnar
Hardness: 7.5 (Mohs scale)
Specific gravity: 3.05 - 3.20
Refractive index: 1.627 - 1.649
Birefringence: -0.007 to -0.013
Optical character:
Color of streak: White
Absorption spectrum: 553, 550, 547, 525, 518, 495, 455, 447, 436
Fluorescence: Weak; green, yellow green
THIS GEM IS NEVER TREATED OR ENHANCED.
FOUND: Deposits are found in Australia, Brazil, Canada, Russia, Spain (Andalusia), Sri Lanka and the United States.
Very rare, collectors gem
