sedimentary
Jasper (Yellow/Brown variety)
Silicon Dioxide (SiO2) - Microcrystalline Quartz
Hardness: 6.5-7 (Mohs scale); Color: Yellow-orange to brownish-red; Luster: Dull to waxy; Crystal Structure: Hexagonal (microcrystalline); Cleavage: None; Specific Gravity: 2.58-2.91
- Hardness
- 6
- Color
- Yellow-orange to brownish-red
- Luster
- Dull to waxy
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Physical properties
Hardness: 6.5-7 (Mohs scale); Color: Yellow-orange to brownish-red; Luster: Dull to waxy; Crystal Structure: Hexagonal (microcrystalline); Cleavage: None; Specific Gravity: 2.58-2.91
Formation & geological history
Formed from the deposition of silica from water solutions into cracks or cavities in other rocks, often in sedimentary environments. Its opaque color is typically caused by high concentrations of iron oxides. These can form in various geological ages worldwide.
Uses & applications
Commonly used for lapidary work, jewelry (cabochons, beads), decorative objects, and as a popular specimen for collectors and rock tumblers.
Geological facts
The name comes from the Greek word 'iaspis', meaning spotted stone. It is an opaque variety of chalcedony. Historically, jasper was a favorite gem in the ancient world, frequently used in seals and amulets.
Field identification & locations
Identify by its opacity (it does not transmit light even on thin edges), its smooth conchoidal fracture, and it cannot be scratched by a steel knife. Commonly found in riverbeds, beaches, and desert plains.
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