igneous
Gold Sheen Obsidian
Volcanic Glass (SiO2 + impurities)
Hardness: 5-5.5; Color: Black with metallic gold sheen; Luster: Vitreous/Submetallic; Structure: Amorphous (glassy); Fracture: Conchoidal
- Hardness
- 5-5
- Color
- Black with metallic gold sheen
- Luster
- Vitreous/Submetallic
Identified More igneous →
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Physical properties
Hardness: 5-5.5; Color: Black with metallic gold sheen; Luster: Vitreous/Submetallic; Structure: Amorphous (glassy); Fracture: Conchoidal
Formation & geological history
Formed by rapid cooling of silica-rich (felsic) lava which prevents crystal growth. Tiny gas bubbles/inclusions are trapped during cooling, creating the gold sheen effect.
Uses & applications
Used extensively in jewelry for cabochons and beads, as well as for decorative carvings, palm stones, and metaphysical purposes.
Geological facts
Unlike typical minerals, obsidian is a 'mineraloid' because it lacks a crystalline structure. The 'gold' effect is caused by tiny patterns of gas bubbles remaining from the original lava flow.
Field identification & locations
Identify by the conchoidal (curved) fracture lines along the edges and the characteristic flash of gold seen when rotated under light. Common in volcanic regions like Mexico and Oregon.
