sedimentary

Chert or flint fragment

Microcrystalline quartz (SiO₂), likely chert/flint

AI-generated identification · may be incorrect

Hardness 6.5–7; pale gray to white, waxy to dull luster, very fine-grained with conchoidal fracture and no visible cleavage. The smooth curved break and semi-translucent edge are characteristic of silica-rich chert.

Identified August 16, 2026More sedimentary →

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Physical properties

Formation & geological history

Forms when microcrystalline quartz replaces or precipitates within marine or freshwater sediments, often from biogenic silica. Individual pieces may be Paleozoic to Cenozoic in age, depending on the deposit.

Uses & applications

Used historically for sharp stone tools and fire-starting; attractive pieces may be tumbled or displayed. Industrial chert is used locally as aggregate and in limited silica applications.

Geological facts

Flint is generally a dark, high-quality variety of chert, while chert includes broader gray, white, red, and brown varieties. Conchoidal fracture can produce extremely sharp edges.

Field identification & locations

Identify it by its glassy-to-waxy appearance, lack of obvious grains, hardness, and curved fracture; it should scratch ordinary glass. Common in limestone beds, river gravels, beaches, and glacial deposits.