sedimentary
Yellow Jasper (Iron-stained Quartz)
Jasper (Silicon Dioxide, SiO2 plus iron oxide impurities)
Hardness: 6.5–7 (Mohs scale), Color: Mustard yellow to brownish-gold with white quartz bands, Luster: Vitreous to waxy, Crystal structure: Trigonal/Microcrystalline/Cryptocrystalline, Cleavage: None (conchoidal fracture), Specific Gravity: 2.6–2.9
- Hardness
- 6
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Physical properties
Hardness: 6.5–7 (Mohs scale), Color: Mustard yellow to brownish-gold with white quartz bands, Luster: Vitreous to waxy, Crystal structure: Trigonal/Microcrystalline/Cryptocrystalline, Cleavage: None (conchoidal fracture), Specific Gravity: 2.6–2.9
Formation & geological history
Formed through the accumulation of silica from either volcanic ash or hydrothermal solutions that permeate through porous rock. Over geological time (often millions of years), the silica crystallizes into a dense, microcrystalline form of quartz, with yellow hues provided by Goethite or Limonite inclusions.
Uses & applications
Commonly used in lapidary work for cabochons, beads, and decorative carvings. In industry, it can be used for mortar and pestles due to its hardness. It is also a popular stone for tumble-polishing and spiritual 'crystal healing' collections.
Geological facts
Jasper has been used as a gemstone since antiquity; it was mentioned in various ancient texts and used for cylinder seals in Mesopotamia. The name is derived from the Greek 'iaspis', meaning 'spotted stone.'
Field identification & locations
Identify in the field by its opaque nature (unlike translucent chalcedony), smooth waxy feel when water-worn, and inability to be scratched by a steel knife. It is frequently found in riverbeds, desert washes, and coastal areas globally, notably in the Western USA, Brazil, and India.
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