sedimentary

Chert (Flint)

Silicon Dioxide (SiO2)

AI-generated identification · may be incorrect

Hardness: 7 (Mohs scale), Color: tan, grey, or translucent brownish, Luster: waxy to dull, Crystal structure: microcrystalline (cryptocrystalline), Cleavage: none (conchoidal fracture), Specific Gravity: 2.65

Identified June 14, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the accumulation of silica-rich organic remains (like diatoms or radiolarians) or through the replacement of limestone. It occurs as nodules or layered deposits in various geological ages ranging from the Precambrian to recent.

Uses & applications

Used historically for stone tools and weapons (knapping), flintlock firearms, and modern decorative landscaping, jewelry (as agate/jasper variants), and industrial abrasives.

Geological facts

Chert was one of the most important materials for early humans due to its ability to split into razor-sharp edges. It is chemically identical to quartz but has a different internal structure.

Field identification & locations

Identify by its characteristic conchoidal (shell-like) fracture and sharp edges. It will scratch glass easily. Commonly found in limestone beds, chalk deposits, or as river cobbles.