igneous
Obsidian
Volcanic Glass (Amorphous SiO2)
AI-generated identification · may be incorrectHardness of 5 to 5.5 on the Mohs scale, typically jet black with a glassy luster and conchoidal fracture. It lacks a true crystalline structure as it is an amorphous mineraloid.
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Physical properties
Hardness of 5 to 5.5 on the Mohs scale, typically jet black with a glassy luster and conchoidal fracture. It lacks a true crystalline structure as it is an amorphous mineraloid.
Formation & geological history
Formed rapidly from felsic lava cooling too quickly for crystal growth, typically in volcanic environments.
Uses & applications
Used historically for sharp cutting tools and arrowheads, and currently in decorative jewelry and ornamental objects.
Geological facts
Despite its dark color, obsidian has a high silica content and produces extremely sharp edges thinner than modern surgical scalpels.
Field identification & locations
Easily identified by its mirror-like shine and distinctive curved conchoidal fracture patterns. Found worldwide near active or recent volcanic regions.
