mineral
Chalcedony Geode Part (Agate/Quartz)
Silicon Dioxide (SiO2)
AI-generated identification · may be incorrectHardness: 6.5-7 on Mohs scale; Color: Grayish-white, translucent; Luster: Waxy to vitreous; Crystal Structure: Trigonal (cryptocrystalline); Cleavage: None (conchoidal fracture); Specific Gravity: 2.58-2.64
- Hardness
- 6
- Color
- Grayish-white, translucent
- Luster
- Waxy to vitreous
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Physical properties
Hardness: 6.5-7 on Mohs scale; Color: Grayish-white, translucent; Luster: Waxy to vitreous; Crystal Structure: Trigonal (cryptocrystalline); Cleavage: None (conchoidal fracture); Specific Gravity: 2.58-2.64
Formation & geological history
Formed via the deposition of silica from groundwater in cavities of volcanic or sedimentary rocks. Over long periods, silica-rich fluids cool or evaporate, leaving behind layers of microcrystalline quartz.
Uses & applications
Used in jewelry (cabochons, beads), micro-precision bearings, as industrial abrasives, and as ornamental display pieces for collectors.
Geological facts
Chalcedony is a cryptocrystalline form of silica, meaning its crystals are too small to be seen without high magnification. When it forms in concentric layers, it is specifically called Agate.
Field identification & locations
Identified by its waxy luster, conchoidal (shell-like) fracture, and inability to be scratched by a steel knife. Commonly found in basaltic lava flows or as nodules in limestone.
