sedimentary

Likely chert/flint fragment

Microcrystalline quartz (SiO₂), possibly partially weathered chert

AI-generated identification · may be incorrect

Dense, fine-grained, opaque gray material with a dull to slightly waxy luster and irregular conchoidal-looking fracture; Mohs hardness about 6.5–7, no visible cleavage, specific gravity roughly 2.6. The white outer material may be weathered silica, carbonate coating, or attached host rock.

Identified August 16, 2026More sedimentary →

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Physical properties

Formation & geological history

Chert forms when silica-rich groundwater replaces or precipitates within limestone, chalk, or marine sediments, commonly during diagenesis; its age depends on the host formation and may range from Paleozoic to Cenozoic. This small piece appears naturally broken or lightly shaped, but the image alone cannot establish provenance.

Uses & applications

Used historically for stone tools and fire-starting, and occasionally as decorative aggregate or lapidary material; ordinary fragments have little commercial value.

Geological facts

Chert is chemically similar to quartz but lacks large visible crystals. Flint is a dark, compact variety of chert, often associated with chalk.

Field identification & locations

Look for a glassy or waxy fracture, sharp edges, strong scratch resistance, and inability to scratch it with a steel nail; fizzing in dilute acid would indicate carbonate rather than pure chert. Common in limestone and chalk regions worldwide.