sedimentary
Jasper Agate (Chalcedony)
Silicon Dioxide (SiO2)
Hardness: 6.5-7 on Mohs scale; Color: Multi-colored with orange, reddish-brown, and grey-white translucency; Luster: Vitreous to waxy; Crystal Structure: Trigonal (Microcrystalline); Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.65
- Hardness
- 6
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 6.5-7 on Mohs scale; Color: Multi-colored with orange, reddish-brown, and grey-white translucency; Luster: Vitreous to waxy; Crystal Structure: Trigonal (Microcrystalline); Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.65
Formation & geological history
Formed through the deposition of silica from groundwater into cavities in igneous or sedimentary rocks. The process often occurs over thousands to millions of years in hydrothermal environments.
Uses & applications
Used primarily for ornamental jewelry, lapidary art, decorative pocket stones, and as a collector's specimen.
Geological facts
Agates and jaspers are both varieties of microcrystalline quartz. Agates are typically translucent and banded, while jasper is opaque. Specimens often blend the two, resulting in 'jaspagate'.
Field identification & locations
Identify in the field by its waxy luster, smoothness after being water-worn, and hardness (it can scratch glass). Commonly found in riverbeds, beaches, and volcanic regions.
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