sedimentary
Red Jasper
Silicon Dioxide (SiO2) with Hematite impurities
Hardness: 6.5-7 (Mohs); Color: Red/Brick-red; Luster: Vitreous to waxy; Structure: Microcrystalline/Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.58-2.91
- Hardness
- 6
- Color
- Red/Brick-red
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 6.5-7 (Mohs); Color: Red/Brick-red; Luster: Vitreous to waxy; Structure: Microcrystalline/Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.58-2.91
Formation & geological history
Formed through the accumulation of fine-grained silica (quartz/chalcedony) in sedimentary environments, often associated with hydrothermal activity or volcanic ash silica. The red color comes from high iron/hematite content.
Uses & applications
Widely used for lapidary work, jewelry (cabochons), polishing in rock tumblers, decorative ornaments, and metaphysical collecting.
Geological facts
The name comes from the Greek word 'iaspis', meaning spotted stone. It was a favorite gemstone in the ancient world, referenced in many historical texts and used in the seals of ancient civilizations.
Field identification & locations
Identify in the field by its opaque nature (it does not transmit light even when held to a bulb), its deep red color, and its ability to scratch glass. Commonly found in riverbeds and coastal regions globally, notably in the USA, India, and Brazil.
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