sedimentary
Red Jasper (Chert)
Silicon dioxide (SiO2) with iron oxide inclusions
Hardness: 6.5-7 (Mohs scale); Color: Brick red to brownish-red; Luster: Dull to waxy; Crystal Structure: Microcrystalline/Trigonal (Cryptocrystalline); Cleavage: None; Specific Gravity: 2.58-2.91
- Hardness
- 6
- Color
- Brick red to brownish-red
- Luster
- Dull to waxy
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Physical properties
Hardness: 6.5-7 (Mohs scale); Color: Brick red to brownish-red; Luster: Dull to waxy; Crystal Structure: Microcrystalline/Trigonal (Cryptocrystalline); Cleavage: None; Specific Gravity: 2.58-2.91
Formation & geological history
Formed from the accumulation of silica-rich micro-organisms or chemical precipitation in sedimentary environments. High iron content provides the red pigment. It can also form during low-grade metamorphism or hydrothermally.
Uses & applications
Used primarily as decorative gemstones, lapidary cabochons, metaphysical healing stones, and historically for making sharp tools/arrowheads due to its conchoidal fracture.
Geological facts
Jasper has been used by ancient civilizations for seals and talismans. It was known as the 'rain bringer' in some Native American traditions. Red Jasper specifically is a common variety of Chalcedony.
Field identification & locations
Identify in the field by its opaque red color and smooth, glass-like conchoidal fractures (curved breaks). It is common in riverbeds and desert environments globally, notably in the USA, Brazil, and India.
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