sedimentary

Chert Pebble (Jasper/Flint variant)

Microcrystalline Quartz (SiO2)

AI-generated identification · may be incorrect

Hardness: 6.5-7 (Mohs), Color: Tan to light brown with subtle banding, Luster: Dull to waxy, Crystal Structure: Cryptocrystalline, Fracture: Conchoidal

Hardness: 6

Identified June 2, 2026More sedimentary →

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Physical properties

Hardness: 6.5-7 (Mohs), Color: Tan to light brown with subtle banding, Luster: Dull to waxy, Crystal Structure: Cryptocrystalline, Fracture: Conchoidal

Formation & geological history

Formed via the accumulation of siliceous remains of marine organisms or chemical precipitation of silica in groundwater. This specimen has been rounded and smoothed by water erosion.

Uses & applications

Historically used for stone tools and fire-starting. Currently used in jewelry (tumbled stones), aquarium decor, and road construction aggregate.

Geological facts

Chert is extremely durable and chemically stable. The fine banding seen at the edge of this specimen indicates rhythmic deposition or varying mineral impurities during formation.

Field identification & locations

Identify by its hardness (scratches glass), smooth texture when water-worn, and conchoidal fracture if chipped. Commonly found on beaches, riverbeds, and in limestone outcrops.