sedimentary

Chert Nodule / Flint

Microcrystalline Quartz (SiO2)

Hardness: 7 on Mohs scale. Color: Gray, tan, brown, and translucent chalcedony/quartz pockets. Luster: Waxy to sub-vitreous. Structure: Cryptocrystalline / Microcrystalline. Fracture: Conchoidal to uneven.

Hardness: 7 on Mohs scale
Color: Gray, tan, brown, and translucent chalcedony/quartz pockets
Luster: Waxy to sub-vitreous

Identified July 23, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed via chemical sedimentation or biochemical processes in shallow marine or freshwater limestone/chalk deposits, where silica precipitates in cavities or replaces existing carbonate minerals over millions of years.

Uses & applications

Historically used for making stone tools, arrowheads, and spark-striking flints. Today, it is mainly collected as a mineral specimen, used as construction aggregate, or polished by lapidaries.

Geological facts

Chert and flint were among the first materials exploited by early humans for fire-starting and tool-making due to their sharp, predictable conchoidal fractures.

Field identification & locations

Identify by its hardness (scratches glass), waxy luster, smooth/glassy fractured surfaces, and frequent association with limestone beds or river deposits. Commonly found worldwide in limestone and dolomite formations.

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