igneous
Mahogany Obsidian
Volcanic Glass with Hematite inclusions (SiO2)
Hardness: 5-5.5 (Mohs scale); Color: Reddish-brown and black streaks; Luster: Vitreous/Glassy; Structure: Amorphous (non-crystalline); Cleavage: Conchoidal fracture; Specific gravity: 2.3 - 2.6.
- Hardness
- 5-5
- Color
- Reddish-brown and black streaks
- Luster
- Vitreous/Glassy
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Physical properties
Hardness: 5-5.5 (Mohs scale); Color: Reddish-brown and black streaks; Luster: Vitreous/Glassy; Structure: Amorphous (non-crystalline); Cleavage: Conchoidal fracture; Specific gravity: 2.3 - 2.6.
Formation & geological history
Formed through the rapid cooling of rhyolitic volcanic lava rich in silica. The brown color is the result of inclusions of Magnetite or Hematite (iron oxides) during the solidification process.
Uses & applications
Used primarily in lapidary work for cabochons, beads, and carvings. Historically used for making sharp tools like arrowheads and knives. Frequently used in metaphysical practices and crystal collecting.
Geological facts
Mahogany Obsidian is technically a natural glass rather than a true mineral because it lacks a crystalline structure. Ancient cultures prized it for surgical-grade sharpness when fractured.
Field identification & locations
Identify by its distinct glass-like texture, lack of visible crystals, and conchoidal (shell-like) fracture patterns. Frequently found in volcanic regions of Mexico, some parts of the Western United States, and Japan.
