igneous
Mahogany Obsidian
Natural Volcanic Glass (SiO2 with iron and magnesium oxides)
Hardness: 5 to 5.5 on the Mohs scale. Color: Deep reddish-brown and black patches or swirls. Luster: Vitreous (glassy). Crystal Structure: Amorphous (non-crystalline). Cleavage: Conchoidal fracture. Specific Gravity: 2.35 to 2.60.
- Hardness
- 5 to 5
- Color
- Deep reddish-brown and black patches or swirls
- Luster
- Vitreous (glassy)
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Physical properties
Hardness: 5 to 5.5 on the Mohs scale. Color: Deep reddish-brown and black patches or swirls. Luster: Vitreous (glassy). Crystal Structure: Amorphous (non-crystalline). Cleavage: Conchoidal fracture. Specific Gravity: 2.35 to 2.60.
Formation & geological history
Formed as felsic lava (rich in silica) cools rapidly with minimal crystal growth, often originating from explosive volcanic eruptions. The reddish-brown coloration is due to the presence of iron oxide or magnetite inclusions within the glass.
Uses & applications
Used primarily for jewelry, polished stones, wire-wrapped pendants, ornamental carvings, and holistic healing or crystal collections.
Geological facts
Obsidian has been used by ancient humans for thousands of years to create sharp cutting tools, arrowheads, and blades due to its exceptionally sharp conchoidal fracture. Mahogany obsidian specifically gets its unique pattern from oxidized iron particles trapped inside the cooling glass.
Field identification & locations
Easily identified by its distinct reddish-brown and black mottled pattern, glassy luster, and conchoidal breakage. Found in regions with past volcanic activity such as the USA (Oregon, California), Mexico, and various global volcanic zones.
