sedimentary
Yellow Jasper
Silicon Dioxide with iron inclusions (SiO2)
Hardness: 6.5-7 on Mohs scale; Color: Mustard yellow to brownish-yellow; Luster: Dull to waxy; Crystal Structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.9
- Hardness
- 6
- Color
- Mustard yellow to brownish-yellow
- Luster
- Dull to waxy
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Physical properties
Hardness: 6.5-7 on Mohs scale; Color: Mustard yellow to brownish-yellow; Luster: Dull to waxy; Crystal Structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.9
Formation & geological history
Formed through the deposition of silica from water-saturated solutions, often in volcanic or sedimentary environments. The yellow color results from the inclusion of iron hydroxides like goethite.
Uses & applications
Used primarily as a lapidary material for jewelry (cabochons, beads), decorative carvings, and as a popular specimen for rock tumbling and metaphysical collections.
Geological facts
Jasper is an opaque variety of chalcedony. It has been used by ancient civilizations for amulets and seals; the name is derived from the Greek 'iaspis', meaning spotted stone.
Field identification & locations
Identify in the field by its opacity (it does not transmit light even on thin edges), its smooth rounded surface if found in riverbeds, and its high hardness which prevents scratching by a steel knife. Common in riverbeds and desert environments globally.
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