sedimentary
Yellow Jasper
Silicon Dioxide (SiO2) with iron oxide inclusions
Hardness: 6.5-7 (Mohs); Color: Yellow to brownish-yellow; Luster: Vitreous to dull; Crystal Structure: Hexagonal (trigonal microcrystalline); Cleavage: None; Specific Gravity: 2.58-2.91
- Hardness
- 6
- Color
- Yellow to brownish-yellow
- Luster
- Vitreous to dull
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Physical properties
Hardness: 6.5-7 (Mohs); Color: Yellow to brownish-yellow; Luster: Vitreous to dull; Crystal Structure: Hexagonal (trigonal microcrystalline); Cleavage: None; Specific Gravity: 2.58-2.91
Formation & geological history
Formed from silica-rich groundwater and fluids that precipitate at low temperatures in fissures or volcanic ash, often associated with sedimentary and metamorphic processes. Most specimens are millions of years old.
Uses & applications
Primarily used in jewelry (beads, cabochons), lapidary art, and as decorative pocket stones or for metaphysical uses.
Geological facts
Jasper is an opaque variety of chalcedony. The yellow coloring is usually caused by the presence of goethite or limonite (iron) inclusions within the quartz matrix.
Field identification & locations
Identify in the field by its hardness (cannot be scratched by a knife), smooth conchoidal fracture, and absolute opacity. Commonly found in riverbeds and deposits in Oregon (USA), Brazil, and Africa.
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