sedimentary (microcrystalline silicate)
Red Jasper (River-worn Pebble)
Silicon Dioxide (SiO2) with Ferric Iron inclusions
Hardness: 6.5–7 on Mohs scale; Color: Reddish-brown, tan, and cream bands; Luster: Dull to waxy when raw; Crystal Structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific Gravity: 2.58–2.91.
- Hardness
- 6
- Color
- Reddish-brown, tan, and cream bands
- Luster
- Dull to waxy when raw
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Physical properties
Hardness: 6.5–7 on Mohs scale; Color: Reddish-brown, tan, and cream bands; Luster: Dull to waxy when raw; Crystal Structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific Gravity: 2.58–2.91.
Formation & geological history
Formed from the deposition of silica-rich fluids in volcanic or sedimentary environments, often associated with iron-rich deposits. This specific specimen has been smoothed and rounded by long-term water erosion in a fluvial (river) or coastal environment.
Uses & applications
Used primarily in lapidary arts, jewelry (cabochons and beads), and as pocket stones. Historically used for making stone tools due to its conchoidal fracturing pattern.
Geological facts
Jasper is an opaque variety of chalcedony. The red color is typically caused by iron oxide (hematite) impurities. It has been used as a gemstone for thousands of years and is mentioned in various ancient cultural texts.
Field identification & locations
Identify in the field by its hardness (cannot be scratched by a steel knife), opacity (it does not transmit light even on thin edges), and smooth, water-worn texture. Commonly found in riverbeds, glacial tills, and along rocky beaches.
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