sedimentary
Yellow Jasper
Chalcedony (SiO2) with goethite or limonite inclusions
Hardness: 6.5–7 on Mohs scale; Color: Opaque yellow to mustard; Luster: Vitreous to waxy; Crystal structure: Trigonal/Microcrystalline; Cleavage: None (conchoidal fracture); Specific gravity: 2.58–2.91
- Hardness
- 6
- Color
- Opaque yellow to mustard
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 6.5–7 on Mohs scale; Color: Opaque yellow to mustard; Luster: Vitreous to waxy; Crystal structure: Trigonal/Microcrystalline; Cleavage: None (conchoidal fracture); Specific gravity: 2.58–2.91
Formation & geological history
Formed through the deposition of silica from hydrothermal solutions or in sedimentary environments where volcanic ash or prehistoric organisms are replaced by silica. Its yellow color comes from iron inclusions. Jasper deposits can range from millions to billions of years old.
Uses & applications
Primary use is in lapidary work for jewelry (cabochons, beads), decorative ornaments, and as a popular pocket stone for collectors and practitioners of crystal healing.
Geological facts
Jasper is an opaque variety of chalcedony. Historically, it was known as the 'supreme nurturer' and has been used by various cultures for talismans and protective amulets. Yellow Jasper specifically has been recorded in use by ancient Egyptian and Native American cultures.
Field identification & locations
Identify by its complete opacity (unlike yellow agate), smooth waxy feel when tumbled, and its inability to be scratched by a steel knife. Common locations include South Africa, Brazil, India, and the USA. Collectors look for consistent deep yellow tones without too many fractures.
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