igneous
Polished mahogany obsidian (likely)
Obsidian, naturally occurring volcanic glass; likely reddish-brown mahogany obsidian
AI-generated identification · may be incorrectPolished, opaque reddish-orange glassy surface with black streaks or patches. Obsidian has Mohs hardness about 5–5.5, no crystal structure, and conchoidal fracture; this small specimen’s properties cannot be confirmed from the image alone.
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Physical properties
Polished, opaque reddish-orange glassy surface with black streaks or patches. Obsidian has Mohs hardness about 5–5.5, no crystal structure, and conchoidal fracture; this small specimen’s properties cannot be confirmed from the image alone.
Formation & geological history
Forms when silica-rich lava cools rapidly, preventing crystals from growing. It is geologically young volcanic glass, commonly associated with Quaternary volcanic deposits.
Uses & applications
Used for ornaments, jewelry, carved objects, and collectibles; historically, sharp obsidian flakes were fashioned into tools and blades.
Geological facts
Mahogany obsidian’s reddish-brown pattern comes from iron-rich inclusions or bands within the glass.
Field identification & locations
Look for a glassy luster, smooth curved fracture surfaces, and dark streaks in a red-brown body. Obsidian occurs in volcanic regions including Mexico, the western United States, and Iceland; the image alone cannot establish the identification.
