Glass / Obsidian

Glass - Leaded glasses are available in all types of colors and refractive indexes.

Obsidian (volcanic siliceous glass)

Type: Apache Tears

Color: Dark gray to brownish-gray. May be transparent, translucent, or nearly opaque.

Moh’s Hardness: 5.5

Refractive Index: 1.48-1.51

Critical Angle: 42.51°

Specific Gravity: 2.3-2.6

Cleavage: None

Fracture: Large conchoidal

Heat Sensitivity: Moderate

Birefringence: None

Crystal Structure: Amorphous

Treatments: Generally none