sedimentary
Chert (Jasper)
Microcrystalline Quartz (SiO2)
Hardness: 6.5-7 (Mohs), Color: Dark greenish-grey with yellow/brown bands, Luster: Waxy to vitreous when polished, Structure: Cryptocrystalline, Fracture: Conchoidal
- Hardness
- 6
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Physical properties
Hardness: 6.5-7 (Mohs), Color: Dark greenish-grey with yellow/brown bands, Luster: Waxy to vitreous when polished, Structure: Cryptocrystalline, Fracture: Conchoidal
Formation & geological history
Formed via the accumulation of silica-rich microfossils or precipitation from hydrothermal fluids in sedimentary basins. The smooth surface suggests water-worn tumbling or manual polishing.
Uses & applications
Historically used for stone tools due to sharp edges; currently used for lapidary work, jewelry, and as a collector's specimen.
Geological facts
Chert and Jasper are among the oldest materials used by humans for weaponry. This specimen shows a waxy luster characteristic of high-silica stones.
Field identification & locations
Identified by its hardness (cannot be scratched by a steel knife) and its smooth, shell-like (conchoidal) fracture patterns. Found in river beds and coastal areas globally.
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