sedimentary

Chert (Jasper/Flint variety)

Silicon dioxide (SiO2) - Microcrystalline Quartz

AI-generated identification · may be incorrect

Hardness: 6.5-7 (Mohs); Color: Brownish-tan with white quartz veining; Luster: Dull to waxy; Structure: Cryptocrystalline; Cleavage: None (Conchoidal fracture); Specific Gravity: 2.6

Hardness: 6
Color: Brownish-tan with white quartz veining
Luster: Dull to waxy

Identified June 11, 2026More sedimentary →

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Physical properties

Hardness: 6.5-7 (Mohs); Color: Brownish-tan with white quartz veining; Luster: Dull to waxy; Structure: Cryptocrystalline; Cleavage: None (Conchoidal fracture); Specific Gravity: 2.6

Formation & geological history

Formed through the accumulation of silica-rich organic remains or chemical precipitation in marine environments and limestone cavities. This specimen shows secondary silica infilling cracks.

Uses & applications

Historically used for stone tools and weapons (flintknapping); currently used for architectural gravel, lapidary tumbling, and jewelry.

Geological facts

This specimen shows distinctive quartz or calcite veins filling stress fractures, creating a spider-web pattern common in septarian-like nodules or weathered river stones.

Field identification & locations

Identify in the field by its hardness (will scratch glass), conchoidal fracture pattern, and waxy texture. Commonly found in riverbeds, glacial tills, and sedimentary basins.