sedimentary

Chert (Flint / Jasper)

Silicon Dioxide (SiO2)

Hardness: 6.5-7 on Mohs scale; Color: yellowish-tan with translucent white quartz areas; Luster: waxy to dull; Cleavage: none (conchoidal fracture); Specific gravity: 2.6-2.7.

Hardness: 6
Color: yellowish-tan with translucent white quartz areas
Luster: waxy to dull

Identified July 23, 2026More sedimentary →

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Physical properties

Hardness: 6.5-7 on Mohs scale; Color: yellowish-tan with translucent white quartz areas; Luster: waxy to dull; Cleavage: none (conchoidal fracture); Specific gravity: 2.6-2.7.

Formation & geological history

Formed through the accumulation and precipitation of microcrystalline silica in marine sedimentary environments or as secondary replacement deposits in limestones.

Uses & applications

Historically used for knapping stone tools, arrowheads, and spark-striking flints. Modern uses include gravel, road base, and decorative specimens.

Geological facts

Chert breaks with extremely sharp edges (conchoidal fracture), which made it one of the most vital raw materials for prehistoric human technology.

Field identification & locations

Identified by its hardness (scratches glass), waxy luster, smooth conchoidal fracture, and yellowish-tan iron oxide staining. Extremely common worldwide in sedimentary rock beds.