sedimentary
Red Jasper
SiO2 (Silicon Dioxide) with Iron oxides
Hardness: 6.5-7 (Mohs scale), Color: Brick red to brownish red, Luster: Vitreous to dull, Structure: Cryptocrystalline quartz (triagonal), Cleavage: None, Specific Gravity: 2.58-2.91
- Hardness
- 6
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Physical properties
Hardness: 6.5-7 (Mohs scale), Color: Brick red to brownish red, Luster: Vitreous to dull, Structure: Cryptocrystalline quartz (triagonal), Cleavage: None, Specific Gravity: 2.58-2.91
Formation & geological history
Formed when fine-grained silica is deposited in sediment or fills cracks in volcanic rocks, with the red color resulting from iron inclusions. Most deposits date from the Precambrian to Cretaceous periods.
Uses & applications
Used extensively in jewelry for cabochons and beads, ornamental carvings, lapidary arts, and historically for tools and seals.
Geological facts
Red Jasper was known as the 'rain bringer' in some ancient cultures and is mentioned in many historical texts for its supposed protective qualities. It is a variety of chalcedony.
Field identification & locations
Identified by its opaque red color, conchoidal fracture, and inability to be scratched by a steel knife. Common in South Africa, Brazil, India, and the USA (Southwest).
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