sedimentary
Yellow Jasper
Silicon Dioxide (SiO2) with Goethite/Iron oxide inclusions
Hardness: 6.5-7 (Mohs scale); Color: Yellow to mustard brown; Luster: Vitreous to waxy; Crystal Structure: Hexagonal (trigonal) microcrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.58-2.91
- Hardness
- 6
- Color
- Yellow to mustard brown
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 6.5-7 (Mohs scale); Color: Yellow to mustard brown; Luster: Vitreous to waxy; Crystal Structure: Hexagonal (trigonal) microcrystalline; 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 sedimentary deposits. The yellow color is primarily due to the presence of goethite or other iron hydroxide minerals. It typically dates from the Proterozoic to Recent periods depending on the specific deposit.
Uses & applications
Used extensively by lapidaries for cabochons, beads, and carvings. Historically used for making tools due to its hardness and sharp conchoidal fracture. It is also popular in metaphysical practices as a 'nurturing' stone.
Geological facts
Jasper is an opaque variety of chalcedony. The name 'jasper' is derived from the Greek 'iaspis', meaning spotted stone. It has been used in jewelry for thousands of years, appearing in artifacts from Ancient Egypt and the Minoan civilization.
Field identification & locations
Identify by its opacity (even on thin edges), smooth waxy feel when polished, and lack of visible crystals. It is commonly found in riverbeds or as nodules in volcanic rocks. Significant deposits are found in India, Russia, Brazil, and the USA (California and Oregon).
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