igneous
Obsidian Arrowhead
Obsidian (Volcanic Glass)
Hardness: 5-5.5 Mohs. Color: Jet black to dark grey. Luster: Vitreous/Glassy. Structure: Amorphous (non-crystalline). Fracture: Conchoidal (shell-like), creating extremely sharp edges.
- Hardness
- 5-5
- Color
- Jet black to dark grey
- Luster
- Vitreous/Glassy
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Physical properties
Hardness: 5-5.5 Mohs. Color: Jet black to dark grey. Luster: Vitreous/Glassy. Structure: Amorphous (non-crystalline). Fracture: Conchoidal (shell-like), creating extremely sharp edges.
Formation & geological history
Formed as an extrusive igneous rock when felsic lava extruded from a volcano cools rapidly with minimal crystal growth. This specimen has been anthropogenically worked through knapping.
Uses & applications
Historically used for hunting tools and weaponry (arrowheads, spears, knives). Currently used in scalpel blades, jewelry, and as archaeological or decorative collectibles.
Geological facts
Obsidian arrowheads can be sharper than high-quality steel surgical scalpels. Many found today are modern reproductions, but ancient ones provide key data on prehistoric trade routes.
Field identification & locations
Identify by its glass-like texture, sharp edges, and repetitive flaking patterns (scars) from the knapping process. Found in volcanic regions like the American West, Mexico, and Iceland.
