igneous
Mahogany Obsidian
Volcanic glass (high silica) with inclusions of Magnetite or Hematite
Hardness: 5-5.5; Color: Brown/Reddish-brown with black swirls/streaks; Luster: Vitreous (glassy); Crystal Structure: Amorphous; Cleavage: None (conchoidal fracture); Specific Gravity: 2.3-2.6
- Hardness
- 5-5
- Color
- Brown/Reddish-brown with black swirls/streaks
- 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: Brown/Reddish-brown with black swirls/streaks; Luster: Vitreous (glassy); Crystal Structure: Amorphous; Cleavage: None (conchoidal fracture); Specific Gravity: 2.3-2.6
Formation & geological history
Formed from the rapid cooling of silica-rich rhyolitic lava. The reddish color comes from inclusions of iron-rich minerals like hematite or magnetite trapped during formation.
Uses & applications
Used primarily in lapidary work for jewelry, decorative carvings, and as a grounding stone in metaphysical practices. Historically used for sharp tools.
Geological facts
Unlike minerals, obsidian is a 'mineraloid' because it cooled too quickly for crystals to grow. It is essentially glass formed by a volcano.
Field identification & locations
Identify by its glass-like texture and characteristic wavy reddish-brown and black patterns. Common in volcanic regions like the American West (Oregon, California) and Mexico.
