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

Identified March 24, 2026More igneous →

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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.

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Igneous

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Magnetite (Fe3O4)

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