sedimentary
Chert (Jasper)
Silicon Dioxide (SiO2)
Hardness: 6.5-7 (Mohs), Color: Multicolored (olive green and reddish-brown), Luster: Waxy to dull, Structure: Cryptocrystalline, Cleavage: None (conchoidal fracture)
- Hardness
- 6
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Physical properties
Hardness: 6.5-7 (Mohs), Color: Multicolored (olive green and reddish-brown), Luster: Waxy to dull, Structure: Cryptocrystalline, Cleavage: None (conchoidal fracture)
Formation & geological history
Formed through the accumulation of silica-rich microfossils (like radiolaria or diatoms) or by chemical precipitation from silica-rich fluids in sedimentary environments.
Uses & applications
Historically used for making stone tools; currently used in jewelry (cabochons), lapidary art, and as decorative stone.
Geological facts
This specimen displays a distinct conchoidal fracture (curved, shell-like breaks) and is a variety of microcrystalline quartz. The coloration is likely due to iron oxide impurities.
Field identification & locations
Identify in the field by its hardness (scratches glass), waxy luster, and sharp edges when broken. Frequently found in riverbeds and sedimentary basins worldwide.
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