sedimentary
Chert Pebble (Jasper variety)
Silicon Dioxide (SiO2)
Hardness: 6.5-7 Mohs; Color: Brown, red, and yellow-ochre; Luster: Waxy to dull; Structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.58-2.91
- Hardness
- 6
- Color
- Brown, red, and yellow-ochre
- Luster
- Waxy to dull
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Physical properties
Hardness: 6.5-7 Mohs; Color: Brown, red, and yellow-ochre; Luster: Waxy to dull; Structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.58-2.91
Formation & geological history
Formed through the accumulation of silica-rich organic remains or chemical precipitation in marine or freshwater environments. This specific specimen shows water-worn rounding from river or stream transport.
Uses & applications
Decorative landscaping, lapidary tumbling, and historically used for stone tools due to its sharp conchoidal fracture.
Geological facts
Jasper is an opaque variety of chalcedony. The patterns and colors are caused by mineral impurities like iron oxides (hematite for red, goethite for yellow/brown).
Field identification & locations
Identify in the field by its smooth, waxy texture and inability to be scratched by a steel pocket knife. Commonly found in riverbeds, glacial tills, and coastal beaches.
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