sedimentary

Chert (variant Flint)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

AI-generated identification · may be incorrect

Hardness: 7 on Mohs scale; Color: Grayish-blue to brownish-white, waxy to dull luster, conchoidal fracture (breaks into sharp, curved edges), trigonal crystal system (microscopic).

Hardness: 7 on Mohs scale

Identified March 8, 2026More sedimentary →

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Physical properties

Hardness: 7 on Mohs scale; Color: Grayish-blue to brownish-white, waxy to dull luster, conchoidal fracture (breaks into sharp, curved edges), trigonal crystal system (microscopic).

Formation & geological history

Formed through the accumulation of silica-rich organic remains (like radiolarians or diatoms) or chemical precipitation from groundwater within sedimentary layers like limestone or chalk.

Uses & applications

Historically used for stone tools and weapons (arrowheads) due to its sharp edges. Modernly used as a jewelry gemstone, in road construction, and for flint-and-steel fire starting.

Geological facts

Flint was one of the first 'high-tech' materials for early humans; it can produce sparks when struck against steel or pyrite, which led to its use in flintlock firearms.

Field identification & locations

Identify in the field by its distinctive 'glassy' conchoidal fracture and its ability to scratch glass. Found globally in nodules within limestone or as river-worn cobbles.