sedimentary

Chert or flint fragment

Microcrystalline quartz (SiO₂), often with chalcedony

AI-generated identification · may be incorrect

Hardness about 7 Mohs; opaque cream to tan, with a dull-to-waxy luster and irregular conchoidal fracture. The fine-grained texture and lack of visible crystals are consistent with chert, though the image alone cannot distinguish it confidently from weathered quartzite or silicified material.

Identified August 11, 2026More sedimentary →

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Physical properties

Formation & geological history

Forms when silica from biogenic debris or groundwater replaces or cements sediment, commonly in limestone or chalk. Most specimens are Paleozoic to Cenozoic, but age depends on its host formation.

Uses & applications

Used historically for sharp tools and fire-starting; attractive varieties are collected and occasionally used for carving or small ornamental pieces. This small fragment has negligible commercial value.

Geological facts

Freshly broken chert produces razor-sharp edges and may show translucent edges. Flint is generally a dark chert variety, so this pale specimen is better called chert unless its source is known.

Field identification & locations

Look for very fine texture, no cleavage, conchoidal fracture, and hardness sufficient to scratch glass; it should not fizz strongly in dilute acid. Common worldwide, especially in limestone and chalk regions.