sedimentary

Dark-colored rough stone, possibly flint or chert

Microcrystalline quartz (SiO₂); identification is uncertain from the image

AI-generated identification · may be incorrect

Opaque, dark gray to black with a dull-to-waxy surface and irregular pale weathering patches. Flint/chert is typically Mohs 7, has no cleavage, and breaks with curved, sharp-edged conchoidal fractures; crystal structure is too fine to see.

Identified October 15, 2026More sedimentary →

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Physical properties

Formation & geological history

Forms when silica-rich material replaces sediment or accumulates in sedimentary settings, often as nodules in limestone or chalk. Its age cannot be determined from appearance alone.

Uses & applications

Flint has historically been used for tools and fire-starting; chert is also used as aggregate and collected as a specimen.

Geological facts

The visible shape and surface are consistent with a weathered silica-rich stone, but the photo does not show diagnostic fracture surfaces.

Field identification & locations

Look for a hard, glassy-to-waxy surface and sharp conchoidal breaks; common in sedimentary terrains worldwide. A scratch test or closer examination would help distinguish it from other dark rocks.