igneous
Mahogany Obsidian
Volcanic glass (SiO2 with Hematite or Magnetite inclusions)
Hardness: 5-5.5; Color: Reddish-brown with black streaks or spots; Luster: Vitreous/Glassy; Structure: Amorphous (non-crystalline); Cleavage: None (conchoidal fracture); Specific Gravity: 2.35-2.6
- Hardness
- 5-5
- Color
- Reddish-brown with black streaks or spots
- Luster
- Vitreous/Glassy
Identified More igneous →
Explore Mahogany Obsidian in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 5-5.5; Color: Reddish-brown with black streaks or spots; Luster: Vitreous/Glassy; Structure: Amorphous (non-crystalline); Cleavage: None (conchoidal fracture); Specific Gravity: 2.35-2.6
Formation & geological history
Formed when felsic lava cools rapidly with minimal crystal growth. The reddish-brown color is caused by high concentrations of iron oxide (hematite) or magnetite during the cooling process. Common in volcanic regions.
Uses & applications
Used in lapidary work for making jewelry, beads, and cabochons. Historically used for making tools like knives and arrowheads because of its sharp conchoidal edges. Also popular for metaphysical and decorative purposes.
Geological facts
Unlike pure black obsidian, Mahogany Obsidian contains iron inclusions that create its unique wavy 'mahogany' patterns. It is technically a glass rather than a true mineral because it lacks a crystalline structure.
Field identification & locations
Look for a smooth, glassy texture and distinctive shell-like (conchoidal) fractures. It is commonly found in the United States (Oregon, California, Utah), Mexico, and Japan.
