igneous
Gold Sheen Obsidian
Volcanic Glass (SiO2 + H2O + Fe2O3)
Hardness: 5-5.5 (Mohs scale); Color: Black with a golden chatoyant luster/sheen; Luster: Vitreous; Crystal Structure: Amorphous (non-crystalline); Cleavage: None, exhibits conchoidal fracture; Specific Gravity: 2.35-2.6
- Hardness
- 5-5
- Color
- Black with a golden chatoyant luster/sheen
- Luster
- Vitreous
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Physical properties
Hardness: 5-5.5 (Mohs scale); Color: Black with a golden chatoyant luster/sheen; Luster: Vitreous; Crystal Structure: Amorphous (non-crystalline); Cleavage: None, exhibits conchoidal fracture; Specific Gravity: 2.35-2.6
Formation & geological history
Formed when gas bubbles from volcanic lava are trapped and stretched during rapid cooling. This occurs in high-silica (rhyolitic) volcanic environments, typically following eruptions from the Holocene epoch back to millions of years ago.
Uses & applications
Primarily used in jewelry (cabochons, pendants), decorative carvings, and as a collector's gemstone. Historically, obsidian was used for making sharp blades and arrowheads.
Geological facts
The golden 'sheen' is caused by tiny bubbles of gas or microscopic inclusions of magnetite trapped as the lava flowed and solidified. It is often referred to as 'Gold Sheen' or 'Golden' obsidian to distinguish it from rainbow or silver sheen varieties.
Field identification & locations
Identify in the field by its distinctive glassy appearance and conchoidal (curved/shell-like) fracture. Commonly found in Mexico, the United States (Oregon, California), and Iceland. For collectors, the intensity and uniformity of the golden sheen determine quality.
