sedimentary
Yellow Jasper
Silicon Dioxide (SiO2) with iron oxide inclusions
Hardness: 6.5-7 (Mohs scale); Color: Yellow to deep mustard with occasional red/orange swirls; Luster: Waxy to dull (vitreous when polished); Crystal Structure: Microcrystalline/Cryptocrystalline (Trigonal); Cleavage: None (conchoidal fracture); Specific Gravity: 2.63 - 2.65
- Hardness
- 6
- Color
- Yellow to deep mustard with occasional red/orange swirls
- Luster
- Waxy to dull (vitreous when polished)
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Physical properties
Hardness: 6.5-7 (Mohs scale); Color: Yellow to deep mustard with occasional red/orange swirls; Luster: Waxy to dull (vitreous when polished); Crystal Structure: Microcrystalline/Cryptocrystalline (Trigonal); Cleavage: None (conchoidal fracture); Specific Gravity: 2.63 - 2.65
Formation & geological history
Formed through the deposition of silica in vents, fissures, or volcanic ash beds during the secondary mineral formation process. Its yellow color comes from the inclusion of Goethite or other iron hydroxides. It is found in geological formations ranging from the Archean to the Cenozoic eras.
Uses & applications
Primarily used for lapidary work, jewelry (cabochons and beads), and ornamental carvings. Industrially, it has historically been used for making scrapers and tools due to its conchoidal fracture, and today it is popular as a grounding stone in the metaphysical market.
Geological facts
Jasper is an opaque variety of chalcedony. The name comes from the Greek word 'iaspis', meaning 'spotted stone'. In ancient times, yellow jasper was believed to protect travelers and provide spiritual guidance.
Field identification & locations
Identify in the field by its opacity (it does not transmit light even on thin edges), its yellow-to-brown streak, and its smooth, waxy feel when water-worn. Common locations include South Africa, Brazil, Madagascar, and the western United States (especially Oregon and Idaho). Collectors should look for smooth, tumbling-ready pieces in riverbeds or desert washes.
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