sedimentary
Chalcedony (Tumbled Agate/Jasper)
Silicon dioxide (SiO2)
Hardness: 6.5-7 (Mohs scale); Color: Tan, beige, translucent white; Luster: Waxy to vitreous; Structure: Microcrystalline quartz; Cleavage: None; Specific Gravity: 2.6
- Hardness
- 6
- Color
- Tan, beige, translucent white
- Luster
- Waxy to vitreous
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Physical properties
Hardness: 6.5-7 (Mohs scale); Color: Tan, beige, translucent white; Luster: Waxy to vitreous; Structure: Microcrystalline quartz; Cleavage: None; Specific Gravity: 2.6
Formation & geological history
Formed from the deposition of silica-rich groundwater in cavities of igneous or sedimentary rocks. This specimen is a water-worn or tumbled river pebble.
Uses & applications
Commonly used in jewelry, lapidary art, and as decorative pocket stones or vase fillers.
Geological facts
Chalcedony is the general term for all microcrystalline quartz varieties. Agate and Jasper are specialized forms of Chalcedony defined by their patterns and transparency.
Field identification & locations
Identified by its waxy luster, conchoidal fracture (visible in the small pit), and inability to be scratched by a steel knife. Commonly found in riverbeds and coastal regions.
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