sedimentary
Jasper / Chert nodule
Microcrystalline Quartz (SiO2)
AI-generated identification · may be incorrectHardness of 6.5-7 on the Mohs scale. Color is reddish-brown top with a greyish-brown base. Luster is dull to slightly waxy where wet. Conchoidal fracture when broken.
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Physical properties
Hardness of 6.5-7 on the Mohs scale. Color is reddish-brown top with a greyish-brown base. Luster is dull to slightly waxy where wet. Conchoidal fracture when broken.
Formation & geological history
Formed from silica-rich fluids precipitating in sedimentary environments or as nodules in limestone/chalk. Often rounded through fluvial or glacial transport.
Uses & applications
Commonly tumbled for amateur collections, used in landscaping, or historically knapped for tools.
Geological facts
The reddish color is typical of jasper, caused by iron oxide inclusions, while the duller grey section is more typical of common chert.
Field identification & locations
Identify by its hardness (scratches glass), smooth texture when water-worn, and opaque appearance. Very common in riverbeds, glacial till, and gravel deposits.
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