sedimentary
Yellow Jasper
Silicon Dioxide (SiO2) with iron oxide inclusions
Hardness: 6.5-7 (Mohs), 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
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Physical properties
Hardness: 6.5-7 (Mohs), 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 accumulation of silica-rich fluids in volcanic ash or sedimentary deposits, often during the Proterozoic or Paleozoic eras. The yellow color comes from high concentrations of goethite or limonite (iron hydroxides).
Uses & applications
Primarily used for lapidary work, jewelry (cabochons, beads), decorative carvings, and as a popular collector specimen for its vibrant color.
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 amulets and seals for thousands of years.
Field identification & locations
Can be identified in the field by its opacity (it does not let light through even at the edges), its smooth conchoidal fracture, and its ability to scratch glass. Commonly found in Western Australia, India, and the United States (Oregon and Idaho).
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