Sphalerite

Color: Green, brown, yellow, red, orange and colorless

Moh’s Hardness: 3.5-4

Refractive Index: 2.268-2.371

Critical Angle: 26.26°

Specific Gravity: 4.08-4.10

Cleavage: Perfect in 6 directions

Fracture: Uneven, brittle

Dispersion: Extremely strong (.156)

Heat Sensitivity: Moderate

Birefringence (double refraction): None

Crystal Structure: Cubic, isometric

Treatments: Generally none