igneous
Obsidian arrowhead
Volcanic glass; predominantly SiO₂, with minor feldspar, pyroxene, and iron oxides
AI-generated identification · may be incorrectBlack to dark gray, vitreous luster, conchoidal fracture, no visible crystals, and Mohs hardness about 5–5.5. The specimen appears pressure-flaked and shaped as a bifacial projectile point, likely human-worked rather than naturally formed.
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Physical properties
Black to dark gray, vitreous luster, conchoidal fracture, no visible crystals, and Mohs hardness about 5–5.5. The specimen appears pressure-flaked and shaped as a bifacial projectile point, likely human-worked rather than naturally formed.
Formation & geological history
Obsidian forms when silica-rich lava cools rapidly, commonly during volcanic eruptions; its volcanic glass may range from recent to millions of years old. The arrowhead was later knapped by humans, potentially prehistoric, though age cannot be determined from the image alone.
Uses & applications
Historically used for arrowheads, knives, and cutting tools because freshly fractured edges are exceptionally sharp; modern obsidian is also collected and occasionally used ornamentally. Archaeological examples may have cultural and research value.
Geological facts
Obsidian lacks a true crystal lattice and is technically a mineraloid. Its composition and trace elements can sometimes identify the geological source through geochemical analysis.
Field identification & locations
Identify by its glassy black appearance, sharp conchoidal edges, and flake scars; distinguish it from flint by its smoother glass-like fracture. Common sources include volcanic regions of Mexico, the western United States, Iceland, Italy, and Japan.
