Mahogany obsidian
Rock
About it
Obsidian mottled and streaked red-brown by iron oxide particles in the glass, beside patches of black. A common tumbled and cabochon stone from Oregon, Utah, and Mexico.
- Type
- Rock (igneous)
- Group
- Igneous (volcanic glass)
- Hardness (Mohs)
- 5–5.5
- Specific gravity
- 2.3–2.6
- Lustre
- vitreous (glassy)
- Colours
- red-brown and black, mottled or streaked
- Transparency
- opaque
- Cleavage and fracture
- none; conchoidal fracture
Typical values: real specimens vary. For more, see mindat.org.