sedimentary

Flint Pebble

Silicon dioxide (microcrystalline quartz / chalcedony)

AI-generated identification · may be incorrect

Hardness: 7 on the Mohs scale; Color: Grey, white, or dark brown/black inside; Luster: Waxy to vitreous; Crystal structure: Microcrystalline/cryptocrystalline; Fracture: Conchoidal; Specific gravity: 2.60-2.65

Hardness: 7 on the Mohs scale
Color: Grey, white, or dark brown/black inside
Luster: Waxy to vitreous

Identified August 5, 2026More sedimentary →

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Physical properties

Formation & geological history

Forms by the replacement of calcium carbonate by silica-rich solutions in chalk or limestone formations during the Cretaceous period, followed by weathering and water-tumbles into smooth pebbles on beaches.

Uses & applications

Historically used for making stone tools, arrowheads, and fire-starting (flintlock firearms); today used as decorative gravel, in construction, and by rock collectors.

Geological facts

Flint is extremely durable and breaks with a very sharp conchoidal fracture, making it one of the most important materials used by early humans for stone tool technology.

Field identification & locations

Commonly found along chalk coastal beaches and riverbeds, easily identified by its smooth, water-worn exterior, waxy texture, and conchoidal chipping.