igneous
Mahogany Obsidian
Volcanic Glass with Hematite/Magnetite inclusions
Hardness: 5 to 5.5 on Mohs scale; Color: Reddish-brown with black spots/streaks; Luster: Vitreous (glassy); Crystal Structure: Amorphous (non-crystalline); Fracture: Conchoidal.
- Hardness
- 5 to 5
- Color
- Reddish-brown with black spots/streaks
- Luster
- Vitreous (glassy)
Identified More igneous →
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Physical properties
Hardness: 5 to 5.5 on Mohs scale; Color: Reddish-brown with black spots/streaks; Luster: Vitreous (glassy); Crystal Structure: Amorphous (non-crystalline); Fracture: Conchoidal.
Formation & geological history
Formed from rapidly cooling rhyolitic lava that had insufficient time to crystallize. The 'mahogany' color is caused by high concentrations of iron oxide (hematite or magnetite) inclusions within the volcanic glass.
Uses & applications
Primarily used for jewelry (beads, cabochons), ornamental carvings, and holistic/collecting purposes. Historically used by ancient cultures for cutting tools and arrowheads.
Geological facts
Obsidian is technically a supercooled liquid rather than a true mineral because it lacks a crystalline structure. Mahogany obsidian is prized for its unique 'leopard' or 'spotted' appearance created by swirling iron-rich minerals.
Field identification & locations
Identify by its glass-like texture, conchoidal fracture, and characteristic reddish-black mottling. Found in volcanic regions including the Western United States (Oregon, California), Mexico, and Japan.
