Mahogany Obsidian

Physical Properties

Hardness: 5-5.5 (Mohs scale), Color: Reddish-brown with black streaks/spots, Luster: Vitreous/Glassy, Structure: Amorphous (non-crystalline), Fracture: Conchoidal, Specific Gravity: 2.4

Formation & Geological History

Formed when rhyolitic volcanic lava cools extremely rapidly, preventing crystal growth. The mahogany color comes from inclusions of Magnetite or Hematite during the cooling process.

Uses & Applications

Used in gemstone carvings, jewelry (cabochons), scalpel blades due to sharpness, and as a popular specimen for metaphysical collectors.

Geological Facts

Because it is a glass rather than a crystal, obsidian breaks with extremely sharp edges. In ancient times, it was used for arrowheads and tools. The 'mahogany' variety is chemically similar to black obsidian but features iron oxide impurities.

Field Identification & Locations

Identified by its signature reddish-brown and black swirling patterns and its smooth, glass-like texture with shell-shaped (conchoidal) fractures. Found in volcanic regions like the American Northwest and Mexico.

Identified on: 5/6/2026

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