sedimentary
Chert / Jasper
Silicon Dioxide (SiO2)
AI-generated identification · may be incorrectHardness: 6.5-7 Mohs; Color: reddish-brown with white/gray inclusions; Luster: waxy to vitreous; Crystal structure: cryptocrystalline (microscopic quartz); Cleavage: none, conchoidal fracture.
- Hardness
- 6
- Color
- reddish-brown with white/gray inclusions
- Luster
- waxy to vitreous
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Physical properties
Hardness: 6.5-7 Mohs; Color: reddish-brown with white/gray inclusions; Luster: waxy to vitreous; Crystal structure: cryptocrystalline (microscopic quartz); Cleavage: none, conchoidal fracture.
Formation & geological history
Formed through the accumulation of silica-rich microfossils or chemical precipitation in marine or volcanic environments; often found in sedimentary beds or as nodules in limestone.
Uses & applications
Historically used for stone tools and arrowheads; modernly used as decorative landscape stone and occasionally for lapidary work/jewelry.
Geological facts
This specimen shows the characteristic waxy luster and jagged fracture lines of microcrystalline quartz. It belongs to the chalcedony family.
Field identification & locations
Identify by its ability to scratch glass and its smooth, shell-like (conchoidal) fracture surfaces that are sharp to the touch. Common worldwide in sedimentary basins.
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