igneous
Mahogany Obsidian
Volcanic Glass with Hematite/Magnetite inclusions (SiO2 + Fe2O3)
Hardness: 5-5.5; Color: Reddish-brown mixed with black; Luster: Vitreous/Glassy; Structure: Amorphous; Cleavage: Conchoidal; Specific Gravity: 2.35-2.6
- Hardness
- 5-5
- Color
- Reddish-brown mixed with black
- Luster
- Vitreous/Glassy
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Physical properties
Hardness: 5-5.5; Color: Reddish-brown mixed with black; Luster: Vitreous/Glassy; Structure: Amorphous; Cleavage: Conchoidal; Specific Gravity: 2.35-2.6
Formation & geological history
Formed when felsic lava cools rapidly with minimal crystal growth. The reddish color comes from inclusions of Hematite or Magnetite during the cooling process in volcanic environments.
Uses & applications
Used primarily for lapidary arts, jewelry (cabochons), palm stones, and decorative carvings or polished towers like the one pictured.
Geological facts
In ancient times, obsidian was used to make extremely sharp arrowheads and blades. Mahogany obsidian is more unique than standard black obsidian due to its distinctive swirling iron-rich patterns.
Field identification & locations
Identify by its glassy texture and distinctive mahogany-red and black wavy patterns. It will exhibit a sharp, shell-like (conchoidal) fracture if broken. Commonly found in areas with recent volcanic activity like Oregon (USA), Mexico, and Japan.
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