sedimentary

Chert (Flint)

Microcrystalline Quartz (SiO2)

AI-generated identification · may be incorrect

Hardness: 7 on Mohs scale; Color: Brown, tan, and grey (likely jasperoid chert); Luster: Waxy to dull; Crystal structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific gravity: 2.65.

Hardness: 7 on Mohs scale
Color: Brown, tan, and grey (likely jasperoid chert)
Luster: Waxy to dull

Identified June 23, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed by the precipitation of silica in sedimentary environments, often replacing carbonate materials in limestone or accumulating from the remains of silica-shelled organisms like dioramas or radiolaria.

Uses & applications

Historically used for making stone tools (arrowheads). Modern uses include construction aggregate, gemstones (when colorful), and fire-starting kits (flint-on-steel).

Geological facts

Chert is so hard it can scratch glass and steel. It was one of the first materials traded globally by prehistoric humans due to its ability to hold a sharp edge.

Field identification & locations

Identify by its conchoidal fracture (curved, shell-like breaks) and waxy texture. It is extremely common in gravel pits, riverbeds, and limestone outcrops worldwide.