sedimentary

Likely pale gray chert (flint) fragment

Microcrystalline quartz (SiO₂), commonly called chert

AI-generated identification · may be incorrect

Opaque, dull gray-beige surface with irregular, possibly conchoidal fracture; quartz hardness 7 and no cleavage. The small, weathered fragment does not show enough detail for a definitive identification.

Identified October 10, 2026More sedimentary →

Explore Likely pale gray chert (flint) fragment in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Forms when silica precipitates or replaces material in sedimentary rocks, often as nodules in limestone or chalk. Chert formed in many geological periods; this specimen’s age and source cannot be determined from the image.

Uses & applications

Chert has historically been used for tools and fire-starting; common fragments have little commercial value.

Geological facts

A fresh break typically has smooth, curved conchoidal surfaces and sharp edges.

Field identification & locations

Look for hardness sufficient to scratch glass and conchoidal fracture; compare with limestone, which is softer and fizzes in dilute acid. Chert occurs worldwide in sedimentary formations.