Mahogany Obsidian

Physical Properties

Hardness: 5-5.5 Mohs; Color: Brown to reddish-black with black inclusions; Luster: Vitreous/Glassy; Structure: Amorphous (Non-crystalline); Fracture: Conchoidal; Specific Gravity: 2.3-2.6

Formation & Geological History

Formed from rapidly cooling silicic lava where cooling occurs too quickly for crystals to grow. The brown/red spots are caused by inclusions of Hematite or Magnetite. Found in Cenozoic volcanic regions.

Uses & Applications

Used in gemstone carvings, cabochons for jewelry, ornamental objects, and holistic/metaphysical practices. Historically used for making sharp tools and arrowheads.

Geological Facts

Unlike minerals, obsidian is a 'mineraloid' because it lacks a crystalline structure. Mahogany obsidian is known for its distinctive 'swirled' look which is unique to each piece based on how the minerals mixed in the lava.

Field Identification & Locations

Identified by its signature conchoidal (shell-like) fracture patterns and glassy texture. Commonly found in areas of recent volcanic activity such as Oregon and California, USA, and Mexico.

Identified on: 5/2/2026

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