sedimentary
Chert (potentially worked flint)
Cryptocrystalline microcrystalline quartz (SiO2)
Hardness: 6.5-7 Mohs; Color: Tan, beige, or brown; Luster: Dull to waxy; Structure: Microcrystalline; Cleavage: None (conchoidal fracture); Opaque.
- Hardness
- 6
- Color
- Tan, beige, or brown
- Luster
- Dull to waxy
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Physical properties
Hardness: 6.5-7 Mohs; Color: Tan, beige, or brown; Luster: Dull to waxy; Structure: Microcrystalline; Cleavage: None (conchoidal fracture); Opaque.
Formation & geological history
Formed via the accumulation of silica-rich organic remains (like diatoms or radiolaria) or chemical precipitation in marine environments, often replacing limestone or chalk.
Uses & applications
Historically used for making stone tools (arrowheads, scrapers) due to its sharp edges when fractured; today used for aggregate or as collector specimens.
Geological facts
While it appears to be a natural chert nodule or fragment, the tapered shape and side protrusion occasionally mimic archaic lithic tools or 'effigy' stones, though this specific piece likely shows natural water-ware or mechanical chipping.
Field identification & locations
Identified by its extremely fine-grained texture and smooth, shell-like (conchoidal) fracture patterns. Frequently found in limestone creek beds or agricultural fields.
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