sedimentary
Chert / Flint Arrowheads
Cryptocrystalline Quartz (SiO2)
Hardness: 7 on the Mohs scale. Color: Dark gray, charcoal, to black. Luster: Vitreous to waxy. Fracture: Conchoidal with sharp edges. Cleavage: None.
- Hardness
- 7 on the Mohs scale
- Color
- Dark gray, charcoal, to black
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 7 on the Mohs scale. Color: Dark gray, charcoal, to black. Luster: Vitreous to waxy. Fracture: Conchoidal with sharp edges. Cleavage: None.
Formation & geological history
Formed by the knapping of sedimentary microcrystalline quartz (flint or chert) by indigenous peoples. The source rock formed in marine sedimentary environments via precipitation of silica.
Uses & applications
Historically used as projectile points, spear tips, and cutting tools. Currently prized as archaeological artifacts, educational display pieces, and collectibles.
Geological facts
These projectile points showcase diagnostic conchoidal fracturing, which ancient stone-tool makers utilized to produce sharp, predictable edges through controlled percussion and pressure flaking.
Field identification & locations
Identify by the presence of knapping scars, sharp edges, symmetrical worked shapes, notch patterns, and conchoidal fractures. Commonly found in archaeological context display frames, farm fields, and river beds in North America.
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