Rock
Obsidian
A volcanic glass formed when silica-rich lava cools too quickly for crystals to grow at all. Its texture is a direct record of the cooling rate.
Classification
- rock class
- igneous
- igneous mode
- extrusive
In the knowledge graph
- Obsidian formed by Magmatic crystallisation
Record last updated 2026-09-06. Corrections follow the published corrections policy; superseded claims are retained, never silently edited.