sedimentary

Weathered chert (flint)

Microcrystalline quartz (SiO₂), also called chalcedony

AI-generated identification · may be incorrect

Hardness about 7 Mohs; gray, tan, and cream mottling with a dull to waxy luster and no visible crystals. It breaks with curved, sharp conchoidal fractures rather than along cleavage planes.

Identified October 4, 2026More sedimentary →

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Physical properties

Hardness about 7 Mohs; gray, tan, and cream mottling with a dull to waxy luster and no visible crystals. It breaks with curved, sharp conchoidal fractures rather than along cleavage planes.

Formation & geological history

Forms when silica precipitates or replaces sediment in limestone and other sedimentary rocks; commonly dates from the host rock’s geological period. The specimen’s exact age and formation setting cannot be determined from the image.

Uses & applications

Chert has been used for tools, construction aggregate, and ornamental objects; attractive pieces may be polished or collected.

Geological facts

Chert is composed mostly of quartz too fine-grained to distinguish individual crystals without magnification.

Field identification & locations

Look for its hardness, waxy surface, and conchoidal fractures; it occurs worldwide, often as nodules or layers in sedimentary formations. The image alone does not confirm the identification.