Zincite (zinc oxide)

Color: Orange, red and yellow, leek-green, light blue to colorless. Moh’s Hardness: 4-4.5

Refractive Index: 2.02

Critical Angle: 29.67°

Specific Gravity: 5.6

Cleavage: Perfect

Fracture: Subconchoidal, brittle

Dispersion: Moderately high to strong.

Heat Sensitivity: Low

Birefringence (double refraction): Medium (.016)

Crystal Structure: Hexagonal

Treatments: None