sedimentary

Yellow Jasper

Chalcedony (Silicon Dioxide, SiO2)

Hardness: 6.5–7 on Mohs scale; Color: Mustard yellow to brownish-yellow with occasional bands; Luster: Vitreous to waxy; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.58–2.91

Hardness: 6
Color: Mustard yellow to brownish-yellow with occasional bands
Luster: Vitreous to waxy

Identified March 28, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the deposition of silica from volcanic ash or sediment-rich water into cracks and cavities. Its yellow color is derived from iron (goethite) inclusions. It can form in various geological ages but is often found in Mesozoic or Cenozoic deposits.

Uses & applications

Used primarily in lapidary arts for cabochons, beads, and pocket stones. Historically used for ornaments and seals. In modern jewelry, it is valued for its earthy aesthetic.

Geological facts

Jasper is an opaque variety of chalcedony. The name comes from the Greek word 'iaspis', meaning 'spotted stone.' Yellow jasper is specifically associated with travelers and was used as an amulet for protection in ancient cultures.

Field identification & locations

Identify in the field by its opacity (unlike translucent agate) and its smooth, rounded appearance when water-worn in riverbeds. It is commonly found in India, Russia, Brazil, and the USA (notably Oregon and Idaho).

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