sedimentary
Jasper (Yellow/Brown variety)
Silicon Dioxide (SiO2) with iron oxide impurities
Hardness: 6.5-7 (Mohs scale); Color: Yellowish-brown to mustard with dark dendritic or spotty inclusions; Luster: Dull to vitreous (waxy); Crystal structure: Microcrystalline/Cryptocrystalline; Cleavage: None (Conchoidal fracture); Specific gravity: 2.58-2.91
- Hardness
- 6
- Luster
- Dull to vitreous (waxy)
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Physical properties
Hardness: 6.5-7 (Mohs scale); Color: Yellowish-brown to mustard with dark dendritic or spotty inclusions; Luster: Dull to vitreous (waxy); Crystal structure: Microcrystalline/Cryptocrystalline; Cleavage: None (Conchoidal fracture); Specific gravity: 2.58-2.91
Formation & geological history
Formed from the deposition of silica-rich fluids in volcanic ash or fine-grained sediments. Over time, the silica crystallizes into microcrystalline quartz, with iron oxides providing the yellow/brown coloration. Can be found in many geological ages from Proterozoic to Cenozoic.
Uses & applications
Commonly used as a gemstone for jewelry (cabochons), interior decoration, ornamental carvings, and widely collected by rockhounds for lapidary work like tumbling and polishing.
Geological facts
Jasper is an opaque variety of chalcedony. The name comes from the Greek word 'iaspis', meaning spotted stone. It was once believed to provide protection against evil spirits and was used in the breastplate of the High Priest in biblical times.
Field identification & locations
Identify by its hardness (cannot be scratched by a steel knife), opaque nature, and smooth water-worn texture if found in riverbanks. It is ubiquitous in gravel beds, desert regions, and mountain runoff areas worldwide. Look for a waxy feel when wet.
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