igneous
Obsidian
Volcanic Glass
AI-generated identification · may be incorrectHardness 5 to 5.5 on Mohs scale, typically jet black with a vitreous luster, conchoidal fracture, and amorphous crystal structure.
Identified More igneous →
Explore Obsidian in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness 5 to 5.5 on Mohs scale, typically jet black with a vitreous luster, conchoidal fracture, and amorphous crystal structure.
Formation & geological history
Formed as extrusive igneous rock when felsic lava cools rapidly with minimal crystal growth.
Uses & applications
Used historically for sharp cutting tools and arrowheads, and currently in jewelry and ornamental sculptures.
Geological facts
Despite its glass-like appearance, it is a naturally occurring volcanic rock rather than man-made glass.
Field identification & locations
Identified easily by its shiny, dark appearance and extremely sharp conchoidal fracture edges; found in regions with recent volcanic activity.
