sedimentary

Weathered chert (flint) pebble

Microcrystalline quartz (SiO₂), commonly called chert or flint

AI-generated identification · may be incorrect

Gray-green with cream weathering patches and a dull-to-waxy luster; likely hardness ~7, conchoidal fracture, and no cleavage. The rounded form suggests water wear; exact identification is uncertain from the photo alone.

Identified October 16, 2026More sedimentary →

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Physical properties

Formation & geological history

Chert forms when silica accumulates and recrystallizes in sedimentary settings, often in limestone or chalk. Its age cannot be determined visually; pebbles are later rounded by transport in streams or shorelines.

Uses & applications

Chert has historically been used for flaked tools and fire-starting; attractive pieces may be collected or used decoratively.

Geological facts

Freshly broken chert typically has a sharp, curved fracture surface and can produce sparks against steel.

Field identification & locations

Look for a dense, fine-grained texture, lack of visible crystals, and conchoidal fracture; common in sedimentary regions and river gravels. A fresh break or hardness test would help confirm it.