sedimentary
Yellow Jasper with Hematite
Silicon Dioxide (SiO2) with Iron Oxide (Fe2O3) inclusions
Hardness: 6.5-7 (Mohs scale); Color: Yellow (due to goethite) with reddish-brown spot (hematite); Luster: Waxy to dull; Crystal structure: Microcrystalline/Trigonal; Cleavage: None (conchoidal fracture); Opaque.
- Hardness
- 6
- Color
- Yellow (due to goethite) with reddish-brown spot (hematite)
- Luster
- Waxy to dull
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Physical properties
Hardness: 6.5-7 (Mohs scale); Color: Yellow (due to goethite) with reddish-brown spot (hematite); Luster: Waxy to dull; Crystal structure: Microcrystalline/Trigonal; Cleavage: None (conchoidal fracture); Opaque.
Formation & geological history
Formed from the precipitation of silica from volcanic ash or hydrothermal fluids in sedimentary environments. The rounded shape indicates extensive water erosion in a beach or river environment. Ages range widely from Precambrian to Cenozoic.
Uses & applications
Primarily used for lapidary work, jewelry (cabochons), river rock landscaping, and as a popular specimen for rock hounds and collectors.
Geological facts
Jasper is an impure variety of silica. The name comes from the Greek word 'iaspis', meaning spotted stone. It is a dense, opaque variety of chalcedony.
Field identification & locations
Identify by its extreme hardness (cannot be scratched by a steel knife), waxy surface when wet, and lack of translucency compared to agate. Commonly found in gravel pits, riverbeds, and coastal beaches.
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