sedimentary

Chert (potentially worked flint)

Cryptocrystalline microcrystalline quartz (SiO2)

AI-generated identification · may be incorrect

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

Identified July 17, 2026More sedimentary →

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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.