igneous
Mahogany Obsidian
Volcanic Glass with Hematite/Magnetite inclusions (SiO2 + Fe2O3)
Hardness: 5-5.5 (Mohs scale); Color: Black with reddish-brown streaks or mottling; Luster: Vitreous (glassy); Crystal Structure: Amorphous (non-crystalline); Specific Gravity: 2.35-2.6.
- Hardness
- 5-5
- Color
- Black with reddish-brown streaks or mottling
- 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 (Mohs scale); Color: Black with reddish-brown streaks or mottling; Luster: Vitreous (glassy); Crystal Structure: Amorphous (non-crystalline); 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 the inclusion of iron oxides like hematite or magnetite during the cooling process.
Uses & applications
Used for carvings, cabochons for jewelry, decorative ornaments, and crystal healing collections. Historically used for making sharp tools like arrows.
Geological facts
Mahogany Obsidian is chemically similar to Rhyolite. It is considered a 'natural glass' and was often traded by ancient civilizations across great distances for tool-making.
Field identification & locations
Identify by its characteristic glassy texture and conchoidal fracture patterns. Found in volcanic regions like the United States (Oregon, California), Mexico, and Japan.
