sedimentary

Likely chert (flint) nodule

Microcrystalline quartz (SiO₂), commonly occurring as a chert nodule

AI-generated identification · may be incorrect

Appears tan and gray-brown with a dull, weathered cortex and darker interior; chert is typically Mohs 7, has a waxy-to-dull luster, and breaks with curved, conchoidal fractures. The image does not show enough detail to confirm its texture or fracture.

Identified October 11, 2026More sedimentary →

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Physical properties

Formation & geological history

Chert forms when silica precipitates or replaces material in sedimentary deposits, often as nodules in limestone or chalk. Its age depends on the host rock and cannot be determined from the photo.

Uses & applications

Chert has been used for stone tools and fire-starting; attractive pieces may be collected or polished, but this specimen appears unworked.

Geological facts

A sharp conchoidal edge and very high hardness are characteristic of chert, historically important for prehistoric cutting tools.

Field identification & locations

Look for a smooth, curved fracture, no visible grains, and the ability to scratch glass; the pale outer rind and dark core fit a possible nodule. Chert occurs worldwide in sedimentary formations.