sedimentary
Yellow Jasper
Chalcedony/Quartz (SiO2) with iron hydroxides (Goethite)
Hardness: 6.5-7 on Mohs scale. Color: Mustard yellow, tan, or gold with earthy bands. Luster: Vitreous to waxy when wet or polished. Structure: Microcrystalline with a conchoidal fracture. Cleavage: None.
- Hardness
- 6
- Color
- Mustard yellow, tan, or gold with earthy bands
- Luster
- Vitreous to waxy when wet or polished
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Physical properties
Hardness: 6.5-7 on Mohs scale. Color: Mustard yellow, tan, or gold with earthy bands. Luster: Vitreous to waxy when wet or polished. Structure: Microcrystalline with a conchoidal fracture. Cleavage: None.
Formation & geological history
Yellow jasper forms through the deposition of silica from hydrothermal fluids or groundwater in volcanic ash or sedimentary beds. Its yellow color comes from the inclusion of goethite or other iron oxides. These stones are often found as water-worn river pebbles or in desert environments.
Uses & applications
Commonly used for lapidary work, decorative cabochons, metaphysical stones, and tumbled landscaping gravel. Historically used for making tools due to its hardness and sharp fracture edges.
Geological facts
Jasper is an opaque variety of chalcedony. The name 'jasper' comes from the Greek word 'iaspis', meaning 'spotted stone'. It is one of the traditional birthstones and has been used in jewelry for thousands of years.
Field identification & locations
Identify in the field by its smooth, water-worn surface, opacity (it will not let light pass through like agate), and extreme hardness (cannot be scratched by a steel knife). Look for it in riverbeds, coastal beaches, and areas with volcanic history.
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