Verdelite Tourmaline

Color: Green, to yellow/green, green/blue

Moh’s Hardness: 7-7.5

Refractive Index: 1.616-1.652

Critical Angle: 38.23°

Specific Gravity: 3.02-3.26

Cleavage: None

Fracture: Uneven, small conchoidal

Dispersion: Medium (.017)

Heat Sensitivity: Not usually a problem

Dichroic: Strong (many color variations)

Birefringence (double refraction): Medium (.014-.024)

Crystal structure: Hexagonal