sedimentary

Chert (Flint)

Silicon Dioxide (SiO2)

AI-generated identification · may be incorrect

Hardness: 7 (Mohs scale); Color: tan, brown, grey, yellowish; Luster: waxy to dull; Crystal structure: Cryptocrystalline (microscopic quartz); Cleavage: none; Fracture: Conchoidal (shell-like curves); Specific Gravity: 2.65.

Hardness: 7 (Mohs scale)
Color: tan, brown, grey, yellowish
Luster: waxy to dull

Identified April 4, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the accumulation of silica-rich organic remains (like radiolaria or diatoms) or by chemical precipitation from groundwater. Often found as nodules within limestone or chalk beds. Age can vary from Precambrian to Cenozoic.

Uses & applications

Historically used for stone tools and weapons. Currently used as a road surfacing material, in construction aggregate, and occasionally in jewelry as or lapidary art when colorful (Jasper/Agate variants).

Geological facts

Chert was one of the most important minerals for early humans because of its ability to break into sharp edges. It is chemically very stable and resistant to weathering.

Field identification & locations

Identify by its 'shell-like' curved fractures, waxy appearance, and extreme hardness (it will easily scratch glass). Look for it in limestone outcrops or as rounded river cobbles.