Rainbow obsidian
Rock
About it
Obsidian that shows bands of iridescent colour when polished and turned in the light, caused by tiny aligned mineral particles in the glass. Best known from Jalisco, Mexico, and Glass Buttes, Oregon.
- Type
- Rock (igneous)
- Group
- Igneous (volcanic glass)
- Hardness (Mohs)
- 5–5.5
- Specific gravity
- 2.3–2.6
- Lustre
- vitreous (glassy)
- Colours
- black with green, purple, gold, or blue sheen bands
- Transparency
- opaque
- Cleavage and fracture
- none; conchoidal fracture
Typical values: real specimens vary. For more, see mindat.org.