sedimentary
Jasper
Silicon dioxide (SiO2)
AI-generated identification · may be incorrectHardness: 6.5-7 (Mohs); Color: Red, brown, and grey patterns; Luster: Dull to greasy; Crystal Structure: Microcrystalline quartz; Cleavage: None, conchoidal fracture
- Hardness
- 6
- Color
- Red, brown, and grey patterns
- Luster
- Dull to greasy
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Physical properties
Hardness: 6.5-7 (Mohs); Color: Red, brown, and grey patterns; Luster: Dull to greasy; Crystal Structure: Microcrystalline quartz; Cleavage: None, conchoidal fracture
Formation & geological history
Formed through the precipitation of silica-rich fluids within volcanic ash or sedimentary beds, often during the Cretaceous period. The red hues are caused by iron inclusions.
Uses & applications
Used primarily as a gemstone in jewelry, for lapidary arts like cabochons, and as decorative ornamental stone.
Geological facts
Jasper is an opaque variety of chalcedony. The word 'jasper' means 'spotted or speckled stone' and it has been used for talismans and jewelry for thousands of years.
Field identification & locations
Identify in the field by its opacity, hardness (will scratch glass), and smooth, waxy fracture surfaces. Commonly found in riverbeds and desert environments.
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Fossil-bearing concretion, possibly containing a fossil shell or other organic inclusion
Calcareous concretion; exact fossil and host-rock composition are not identifiable from the image
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Fossiliferous Sedimentary Rock
Sedimentary limestone with invertebrate fossil imprint
fossil
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Sandstone
Arenite
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Shale
Shale (clastic sedimentary rock)
sedimentary
Shale (or Mudstone/Siltstone)
Sedimentary Mudrock (SiO2, Al2O3 base with clay minerals)
sedimentary