igneous
Black obsidian arrowhead
Obsidian (volcanic glass), primarily silica-rich rhyolitic composition
AI-generated identification · may be incorrectUsually black with vitreous luster and sharp conchoidal fracture; amorphous rather than crystalline, hardness about 5–5.5 Mohs, and no cleavage. The flaked, pointed form is human-worked and resembles an arrowhead or blade.
Identified More igneous →
Explore Black obsidian arrowhead in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Usually black with vitreous luster and sharp conchoidal fracture; amorphous rather than crystalline, hardness about 5–5.5 Mohs, and no cleavage. The flaked, pointed form is human-worked and resembles an arrowhead or blade.
Formation & geological history
Obsidian forms when silica-rich lava cools extremely rapidly, preventing crystal growth; deposits are generally Quaternary to older Cenozoic. This specimen appears knapped from volcanic glass, though the image alone cannot confirm authenticity or age.
Uses & applications
Historically used for arrowheads, knives, and scraping tools because it produces exceptionally sharp edges; modern material is used for ornaments, jewelry, cabochons, and collectibles.
Geological facts
Fresh obsidian flakes can be sharper than surgical steel edges, but they are brittle and easily damaged. Common varieties include snowflake, mahogany, rainbow, and sheen obsidian.
Field identification & locations
Identify by its glassy black surface, very sharp conchoidal flakes, lack of visible crystals, and typically lightweight feel; common sources include Mexico, the western United States, Armenia, Turkey, and Japan. Archaeological provenance and confirmed age greatly affect value.
