sedimentary
Jasper (specifically Yellow Jasper and Red Jasper)
Silicon Dioxide (SiO2) with iron oxide inclusions
Hardness: 6.5-7 (Mohs scale), Color: Mustard yellow and brick red, Luster: Dull to vitreous, Crystal Structure: Microcrystalline/Cryptocrystalline, Cleavage: None (conchoidal fracture)
- Hardness
- 6
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Physical properties
Hardness: 6.5-7 (Mohs scale), Color: Mustard yellow and brick red, Luster: Dull to vitreous, Crystal Structure: Microcrystalline/Cryptocrystalline, Cleavage: None (conchoidal fracture)
Formation & geological history
Formed from the deposition of silica from water-rich environments, often in volcanic ash or sedimentary deposits where silica replaces organic material or fills voids. Colors are derived from high iron content (Goethite for yellow, Hematite for red).
Uses & applications
Commonly used in lapidary arts for jewelry, beads, cabochons, and ornamental carvings. Historically used for making tools due to its sharp conchoidal fracture.
Geological facts
Jasper has been used as a gemstone since antiquity and was frequently mentioned in historical texts as a 'supreme nurturer.' Its name is derived from the Greek word 'iaspis,' meaning spotted stone.
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 found in many worldwide locations including India, Brazil, and the Southwestern USA.
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