sedimentary

Chert (Jasper variety)

Silicon Dioxide (SiO2)

AI-generated identification · may be incorrect

Hardness: 6.5-7 on Mohs scale; Color: Yellowish-brown, tan, with darker stripes; Luster: Waxy to dull; Crystal structure: Microcrystalline/Cryptocrystalline quartz; Cleavage: None (conchoidal fracture).

Hardness: 6
Color: Yellowish-brown, tan, with darker stripes
Luster: Waxy to dull

Identified April 25, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the accumulation of silica-rich microfossils or chemical precipitation of silica in marine or groundwater environments. This specimen appears as a water-worn pebble, likely from a river or glacial deposit.

Uses & applications

Used historically for stone tools due to sharp edges; currently used for lapidary work, jewelry (beads/cabochons), and as aquarium or decorative stone.

Geological facts

Chert is so durable that it can survive long-distance transport in rivers and glacial till. High-quality colored chert is often referred to as Jasper.

Field identification & locations

Identify by its hardness (cannot be scratched by a steel knife) and its smooth, waxy texture. Commonly found in gravel pits, river beds, and coastal erosion zones.