sedimentary
Red Jasper
Silicon Dioxide (SiO2) with Iron Oxide (Fe2O3)
Hardness: 6.5-7 Mohs; Color: Brick red to brownish red; Luster: Dull to Vitreous; Crystal Structure: Microcrystalline/Trigonal; Cleavage: None; Specific Gravity: 2.58-2.91
- Hardness
- 6
- Color
- Brick red to brownish red
- Luster
- Dull to Vitreous
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Physical properties
Hardness: 6.5-7 Mohs; Color: Brick red to brownish red; Luster: Dull to Vitreous; Crystal Structure: Microcrystalline/Trigonal; Cleavage: None; Specific Gravity: 2.58-2.91
Formation & geological history
Formed from the deposition of silica-rich sediments or volcanic ash where iron impurities provide the red pigment. It typically occurs as nodules or in fissures across various geological eras.
Uses & applications
Used primarily as a gemstone for jewelry, lapidary work (cabochons), or decorative carvings. Historically used for making tools like scrapers and arrowheads due to its conchoidal fracture.
Geological facts
Ancient Egyptians often wore red jasper amulets to symbolize the blood of Isis. It is a variety of chalcedony that is considered opaque compared to translucent agates.
Field identification & locations
Identify by its opaque red color and smooth, shell-like (conchoidal) fracture pattern. It is commonly found in the western USA, Brazil, India, and South Africa. Collectors should look for vibrant saturation and absence of large cracks.
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