sedimentary
Yellow Jasper (Beach Pebble)
Silicon Dioxide (SiO2) with iron hydroxide impurities
Hardness: 6.5-7 on Mohs scale; Color: Mustard to pale yellow; Luster: Vitreous to dull/waxy when dry; Structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.58-2.91.
- Hardness
- 6
- Color
- Mustard to pale yellow
- Luster
- Vitreous to dull/waxy when dry
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Physical properties
Hardness: 6.5-7 on Mohs scale; Color: Mustard to pale yellow; Luster: Vitreous to dull/waxy when dry; Structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.58-2.91.
Formation & geological history
Formed through the deposition of silica-rich fluids in volcanic ash or sedimentary beds, often during the Proterozoic to Cenozoic eras. This specimen has been rounded and smoothed via long-term water erosion (abrasion) in a high-energy beach or river environment.
Uses & applications
Used primarily for jewelry (cabochons, beads), decorative lapidary arts, and stone healing practices. In larger quantities, jasper is used in aquarium decor and landscaping.
Geological facts
Jasper is an opaque variety of chalcedony. The yellow hue is typically caused by the presence of goethite or other iron oxyhydroxides. Historically, it was known as a 'rain bringer' in some indigenous cultures.
Field identification & locations
Identify in the field by its opacity (it will not let light pass through like quartz), its smoothness, and its ability to scratch glass. Commonly found on pebble beaches, dry riverbeds, and in glacial till across North America and Europe.
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