igneous
Obsidian
Volcanic glass
AI-generated identification · may be incorrectHardness 5-5.5, deep black or dark green color, vitreous luster, amorphous crystal structure with distinct conchoidal fracture.
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 5-5.5, deep black or dark green color, vitreous luster, amorphous crystal structure with distinct conchoidal fracture.
Formation & geological history
Formed as extrusive igneous rock when felsic lava cools rapidly with minimal crystal growth.
Uses & applications
Historically used for sharp cutting tools, arrowheads, and blades; currently valued in ornamental jewelry and lapidary work.
Geological facts
Despite lacking a true crystalline lattice, obsidian is classified as a mineraloid rather than a true mineral.
Field identification & locations
Easily identified by its glassy appearance, sharp conchoidal fracture edges, and dark translucent quality when held to light.
