sedimentary
Red Jasper (Opaque Chalcedony)
Silicon Dioxide (SiO2) with Iron Oxide (Fe2O3) inclusions
Hardness: 6.5-7 (Mohs scale); Color: Brick red to brownish-red with white or tan spots; Luster: Vitreous to waxy; Crystal structure: Trigonal/Microcrystalline; Cleavage: None (Conchoidal fracture); Specific gravity: 2.58-2.91.
- Hardness
- 6
- Color
- Brick red to brownish-red with white or tan spots
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 6.5-7 (Mohs scale); Color: Brick red to brownish-red with white or tan spots; Luster: Vitreous to waxy; Crystal structure: Trigonal/Microcrystalline; Cleavage: None (Conchoidal fracture); Specific gravity: 2.58-2.91.
Formation & geological history
Formed through the process of mineral-rich water depositing microcrystalline silica in cavities or through the chemical precipitation of silica. Its red color comes from iron oxide (hematite) impurities integrated during formation, often in hydrothermal or volcanic environments.
Uses & applications
Primarily used for lapidary work, jewelry (cabochons and beads), ornamental carvings, and as a popular semi-precious stone for collectors and metaphysical practices.
Geological facts
Jasper has been used by humans for thousands of years; it was mentioned in various ancient religious texts and was used by ancient civilizations for seals and talismans. It is known as the 'Supreme Nurturer' in gemstone folklore.
Field identification & locations
Identify in the field by its distinctive brick-red color, extreme hardness (it will scratch glass), and its lack of transparency even when held to light. Often found in gravel pits, riverbeds, or as nodules in volcanic rock. Common locations include India, Brazil, USA (Oregon, Idaho), and South Africa.
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