sedimentary

Chert (specifically Red Chert/Jasper nodule)

Microcrystalline Quartz (SiO2)

AI-generated identification · may be incorrect

Hardness: 6.5–7 (Mohs scale); Color: Red, maroon, and white banding; Luster: Vitreous to waxy; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.65.

Hardness: 6
Color: Red, maroon, and white banding
Luster: Vitreous to waxy

Identified March 18, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the accumulation of silica-rich organic remains (like diatoms or radiolarians) or chemical precipitation from hydrothermal fluids in sedimentary environments. The red color is caused by iron oxide inclusions.

Uses & applications

Used historically for stone tools (arrowheads/scrapers) due to conchoidal fracturing. Modern uses include decorative landscaping, lapidary work (cabochons), and as an industrial abrasive.

Geological facts

Red chert is often termed 'Jasper' when it is opaque. It was one of the most vital materials for prehistoric humans because it can be knapped into extremely sharp edges.

Field identification & locations

Identify in the field by its smooth, waxy surface and sharp, curved (conchoidal) edges where broken. It is harder than steel and will scratch glass. Commonly found in riverbeds or limestone deposits.