sedimentary (or mineraloid)
Yellow Jasper
Jasper (Silicon Dioxide, SiO2)
Hardness: 6.5–7 on Mohs scale; Color: Mustard yellow to golden brown; Luster: Dull to greasy; Crystal Structure: Microcrystalline (Trigonal); Cleavage: None (conchoidal fracture); Specific Gravity: 2.58–2.91.
- Hardness
- 6
- Color
- Mustard yellow to golden brown
- Luster
- Dull to greasy
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Physical properties
Hardness: 6.5–7 on Mohs scale; Color: Mustard yellow to golden brown; Luster: Dull to greasy; Crystal Structure: Microcrystalline (Trigonal); Cleavage: None (conchoidal fracture); Specific Gravity: 2.58–2.91.
Formation & geological history
Formed through the infiltration of silica-rich fluids into volcanic ash or fine-grained sediments. Over time, the silica crystallizes into microcrystalline quartz. The yellow hue is primarily due to the presence of goethite or other iron hydroxides trapped during formation.
Uses & applications
Predominantly used as a gemstone for lapidary work (cabochons and beads), decorative ornaments, and in holistic practices. Historically used for making tools due to its conchoidal fracture which creates sharp edges.
Geological facts
Jasper is an opaque variety of chalcedony. The name 'jasper' is derived from the Greek word 'iaspis', meaning 'spotted stone.' Yellow jasper has been used since antiquity for ornaments and was highly valued in ancient Egyptian and Greek cultures.
Field identification & locations
Identify in the field by its smooth, waxy surface when broken and its inability to be scratched by a steel knife. It is frequently found in stream beds or as weathered nodules in desert environments. Common locations include the Western USA, Brazil, South Africa, and India.
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