sedimentary

Chert (Jasper variation)

Silicon Dioxide (SiO2)

Hardness: 6.5-7 (Mohs scale); Color: Brownish-red to dark brown; Luster: Waxy to dull; Crystal structure: Microcrystalline/Cryptocrystalline; Conchoidal fracture; Opaque.

Hardness: 6
Color: Brownish-red to dark brown
Luster: Waxy to dull

Identified July 20, 2026More sedimentary →

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Physical properties

Hardness: 6.5-7 (Mohs scale); Color: Brownish-red to dark brown; Luster: Waxy to dull; Crystal structure: Microcrystalline/Cryptocrystalline; Conchoidal fracture; Opaque.

Formation & geological history

Formed from the replacement of organic materials or the precipitation of silica-rich fluids in sedimentary basins. Most chert/jasper dates from various eras, frequently found in ancient seafloor deposits.

Uses & applications

Used historically for stone tools and weapons due to its sharp edges when fractured. Today, it is used for lapidary work, jewelry, and as a decorative garden stone.

Geological facts

It is a microcrystalline variety of quartz. The specific circular patterns visible on the surface could indicate oolitic structures or small fossilized inclusions common in jasper and chert nodules.

Field identification & locations

Identify in the field by its hardness (will scratch glass), conchoidal (shell-like) fracture patterns, and smooth, waxy feel. Common in riverbeds, glacial tills, and sedimentary rock formations worldwide.