
sedimentary
Jasper
Silicon dioxide (SiO2)
AI-generated identification · may be incorrectHardness: 6.5-7 (Mohs); Color: tan, yellow, orange-ish; Luster: vitreous to waxy; Structure: cryptocrystalline quartz; Cleavage: none (conchoidal fracture).
- Hardness
- 6
- Color
- tan, yellow, orange-ish
- Luster
- vitreous to waxy
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Physical properties
Hardness: 6.5-7 (Mohs); Color: tan, yellow, orange-ish; Luster: vitreous to waxy; Structure: cryptocrystalline quartz; Cleavage: none (conchoidal fracture).
Formation & geological history
Formed from silica-rich fluids circulating through volcanic ash or sedimentary layers. This process of petrification or chemical precipitation occurs over millions of years, typically during the Cretaceous to Tertiary periods.
Uses & applications
Commonly used as a gemstone, for lapidary work (cabs and beads), decorative ornaments, and healing crystals in various cultures.
Geological facts
Jasper is an opaque variety of chalcedony. It takes such a high polish that it has been used historically for making seals and vases in ancient Mediterranean civilizations.
Field identification & locations
Identify by its high hardness (won't be scratched by a steel knife) and its smooth, waxy feel. Often found in riverbeds, coastal gravels, or desert regions worldwide, particularly in the western USA (Oregon, Idaho).
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Fossiliferous Sedimentary Rock
Sedimentary limestone with invertebrate fossil imprint
fossil
Sandstone or Siltstone
Arenite (if sandstone)
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Sandstone
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Shale
Shale (clastic sedimentary rock)
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Shale (or Mudstone/Siltstone)
Sedimentary Mudrock (SiO2, Al2O3 base with clay minerals)
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