Rock Identifier
Chert (Jasper variation) (Silicon Dioxide (SiO2)) — sedimentary
sedimentary

Chert (Jasper variation)

Silicon Dioxide (SiO2)

AI-generated identification · may be incorrect

Hardness: 6.5-7 (Mohs scale); Color: Reddish-brown with tan/white bands; Luster: Waxy to dull; Crystal structure: Microcrystalline (trigonal); Cleavage: None (conchoidal fracture); Specific gravity: 2.6-2.7

Hardness
6
Color
Reddish-brown with tan/white bands
Luster
Waxy to dull
Identified More sedimentary →
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Physical properties

Hardness: 6.5-7 (Mohs scale); Color: Reddish-brown with tan/white bands; Luster: Waxy to dull; Crystal structure: Microcrystalline (trigonal); Cleavage: None (conchoidal fracture); Specific gravity: 2.6-2.7

Formation & geological history

Formed through the accumulation of silica-rich organic remains or chemical precipitation in sedimentary environments. Can form as nodules or bedded deposits throughout various geological ages.

Uses & applications

Commonly used for lapidary work (jewelry, cabochons), primitive tool making (arrowheads), and as a collector's specimen.

Geological facts

Chert was one of the most important minerals for early humans because its conchoidal fracture creates razor-sharp edges used for blades and scrapers.

Field identification & locations

Identify in the field by its waxy luster and smooth, curved (conchoidal) breaks. It is commonly found in limestone or dolomite beds globally.

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