sedimentary
Chert (Jasper variation)
Silicon Dioxide (SiO2)
Hardness: 6.5-7 Mohs; Color: reddish-brown with white quartz veining; Luster: waxy to dull; Crystal structure: cryptocrystalline; Cleavage: none, conchoidal fracture.
- Hardness
- 6
- Color
- reddish-brown with white quartz veining
- Luster
- waxy to dull
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Physical properties
Hardness: 6.5-7 Mohs; Color: reddish-brown with white quartz veining; Luster: waxy to dull; Crystal structure: cryptocrystalline; Cleavage: none, conchoidal fracture.
Formation & geological history
Formed through the accumulation of silica-rich microfossils or chemical precipitation in marine or volcanic environments, often during the Paleozoic era.
Uses & applications
Historical use for stone tools/arrowheads; contemporary use in landscaping, decorative stone, and occasionally lapidary craft.
Geological facts
The reddish color is typically caused by iron oxide impurities. It is very resistant to physical weathering and chemical erosion.
Field identification & locations
Look for a microcrystalline texture, conchoidal fracture patterns, and its ability to scratch glass. Found in riverbeds and sedimentary basins worldwide.
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