sedimentary

Possible flint (dark chert) nodule

Microcrystalline quartz (SiO₂), commonly called chert or flint

AI-generated identification · may be incorrect

Dark gray to black, dull-to-waxy luster, and very fine-grained with no visible crystals; quartz hardness is about 7 Mohs and it breaks with curved, sharp-edged conchoidal fractures. The image is insufficient to confirm the identification; the pale markings may be inclusions or surface deposits.

Identified September 28, 2026More sedimentary →

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Physical properties

Formation & geological history

Chert forms when silica accumulates and hardens in sedimentary settings, often replacing carbonate sediment; its age depends on the host formation. The specimen’s geological age and origin cannot be determined from the photo.

Uses & applications

Flint has historically been used for tools and fire-starting; chert is also collected and sometimes used as decorative stone or aggregate.

Geological facts

Freshly fractured flint can produce exceptionally sharp edges. The pictured object’s rounded, irregular shape is consistent with a nodule, but is not diagnostic.

Field identification & locations

Look for a very fine texture and sharp, curved fracture surfaces; a fresh break is more informative than this weathered exterior. Chert occurs worldwide in sedimentary rocks, but location is unknown here.