Archive for the Andalusite Category

Viridine

Refractive Index : 1.643 – 1.634 (+ 0.005 – 0.005)

Optical Characteristic : DR, Biaxial negative, AGG

Specific Gravity : 3.17 + 0.04 – 0.04

Formula : AI2SiO5=AI[6]A[5]OSiO4

Crystal System : Orthorhombic

Variety/Species : Andalusite

Species/Group : Andalusite

Birefringence : 0.007 – 0.003

Dispersion : 0.016

Hardness : 7 to 7.5

Toughness : Fair to good

Ultrasonic : Uaually safe

Steam : Risky

UV Long : Inert

UV Short [...]