sedimentary
Chert (Arrowheads)
Microcrystalline Quartz (SiO2)
Hardness: 6.5-7 Mohs; Color: Brown, tan, reddish-orange; Luster: Waxy to vitreous; Structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65
- Hardness
- 6
- Color
- Brown, tan, reddish-orange
- Luster
- Waxy to vitreous
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Physical properties
Hardness: 6.5-7 Mohs; Color: Brown, tan, reddish-orange; Luster: Waxy to vitreous; Structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65
Formation & geological history
Formed through the accumulation of silica-rich organic remains or chemical precipitation in sedimentary basins. These specific pieces are anthropogenic artifacts (lithic projectiles) carved from raw chert nodules.
Uses & applications
Historically used for tools and weapons due to sharp edges; currently valued as archaeological artifacts and collectibles.
Geological facts
Chert and flint were the primary materials for stone tool technology for millions of years because of their predictable conchoidal fracturing and extreme sharpness.
Field identification & locations
Identify by the 'flake' scars from knapping (shaping process) and the shell-like (conchoidal) curves where the stone was struck. Commonly found in riverbeds or prehistoric site areas.
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Cone-in-cone structure (Secondary Sedimentary Structure)
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