igneous
Mahogany Obsidian
Obsidian (volcanic glass with hematite/magnetite inclusions)
Hardness: 5-5.5 (Mohs scale); Color: Black with reddish-brown (mahogany) streaks; Luster: Vitreous/Glassy; Structure: Amorphous (non-crystalline); Cleavage: Conchoidal fracture; Specific gravity: 2.3-2.6
- Hardness
- 5-5
- Color
- Black with reddish-brown (mahogany) streaks
- Luster
- Vitreous/Glassy
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Physical properties
Hardness: 5-5.5 (Mohs scale); Color: Black with reddish-brown (mahogany) streaks; Luster: Vitreous/Glassy; Structure: Amorphous (non-crystalline); Cleavage: Conchoidal fracture; Specific gravity: 2.3-2.6
Formation & geological history
Formed from rapidly cooling felsic lava where crystallization does not occur. The reddish color is caused by the presence of oxidized iron (hematite or magnetite) trapped within the glass during cooling.
Uses & applications
Used primarily for lapidary arts, jewelry (beads, cabochons), ornamental carvings, and holistic/metaphysical collecting. Historically used for sharp tools due to its fracture patterns.
Geological facts
Despite looking like a mineral, obsidian is technically a 'mineraloid' because it lacks a crystal structure. Mahogany obsidian is known for being gentler in its appearance than pure black obsidian due to the iron-rich swirls.
Field identification & locations
Identify by its distinctive glassy texture and mahogany-colored undulating bands or ripples. Commonly found in areas with recent volcanic activity like Mexico, USA (Oregon, California), and Japan.
