sedimentary

Chert / Flint

Silicon Dioxide (SiO2) - Microcrystalline Quartz

Hardness: 6.5-7 Mohs scale. Color: Brownish-tan to yellowish-grey, translucent at thin edges. Luster: Waxy to sub-vitreous. Fracture: Distinct conchoidal fracture with smooth, curved surfaces and sharp edges.

Hardness: 6
Color: Brownish-tan to yellowish-grey, translucent at thin edges
Luster: Waxy to sub-vitreous

Identified July 27, 2026More sedimentary →

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Physical properties

Formation & geological history

Biogenic or chemical sedimentary origin, formed from the precipitation of silica-rich fluids or accumulation of siliceous microscopic organisms (like radiolarians and diatoms) in marine or freshwater sedimentary environments.

Uses & applications

Historically used for stone tools, arrowheads, and flintlock firearms due to its sharp conchoidal edges. Currently used in road construction base, decorative landscaping pebbles, and LAPIDARY applications.

Geological facts

Chert and flint were among the first materials shaped by early humans to make primitive cutting tools and fire-starters due to their reliable conchoidal fracturing and ability to spark when struck against iron/pyrite.

Field identification & locations

Identify by its waxy texture, smooth curved fractures, hard surface that scratches steel, and translucent edges under light. Common along gravel bars, river beds, and limestone/chalk formations worldwide.

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