sedimentary

Likely chert (flint) pebble

Microcrystalline quartz (SiO₂), variety chert

AI-generated identification · may be incorrect

Dull gray-brown, smooth and fine-grained; quartz hardness about 7, Mohs, with no visible crystals or cleavage. The photo alone cannot confirm its composition; a fresh break would typically be waxy and produce a sharp, curved fracture.

Identified October 10, 2026More sedimentary →

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Physical properties

Formation & geological history

Chert forms when silica precipitates or accumulates in sediment, often replacing limestone; its age depends on the deposit and cannot be determined from the image.

Uses & applications

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

Geological facts

Chert can resemble other smooth, fine-grained stones, including limestone and mudstone.

Field identification & locations

This appears to be a small, rounded pebble, but identification is uncertain without a fresh surface or hardness test. Chert occurs worldwide in sedimentary formations and stream gravels.