sedimentary

Chert (Jasper variety)

Silicon Dioxide (SiO2)

AI-generated identification · may be incorrect

Hardness: 6.5-7 (Mohs scale), Color: Dark brown to yellow-brown, Luster: Waxy to dull, Crystal structure: Microcrystalline (Trigonal system), Cleavage: None (conchoidal fracture), Specific Gravity: 2.65

Hardness: 6

Identified March 9, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the accumulation of silica-rich microfossils or precipitation from silica-rich groundwater within sedimentary rock layers. This specimen shows signs of stream-tumbling/weathering which rounds the edges.

Uses & applications

Used ornamentally as gemstones, in decorative landscaping, and historically for making sharp tools like arrows and scrapers due to its conchoidal fracturing.

Geological facts

Chert and its variety Jasper were among the first resources used by early humans for tool-making because it breaks into razor-sharp edges. Its dense structure makes it very durable over geological time.

Field identification & locations

Identify in the field by its hardness (will scratch glass), waxy luster when broken, and lack of visible grains. Commonly found in riverbeds, glacial tills, and limestone deposits globally.