mineral
Chalcedony (Blue Dragon/Gray Chalcedony)
Silicon Dioxide (SiO₂)
Hardness: 6.5-7 Mohs; Color: Bluish-gray, semi-translucent; Luster: Waxy to vitreous; Crystal Structure: Cryptocrystalline (Trigonal/Monoclinic); Cleavage: None; Fracture: Conchoidal; Specific Gravity: 2.6-2.64
- Hardness
- 6
- Color
- Bluish-gray, semi-translucent
- Luster
- Waxy to vitreous
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Physical properties
Hardness: 6.5-7 Mohs; Color: Bluish-gray, semi-translucent; Luster: Waxy to vitreous; Crystal Structure: Cryptocrystalline (Trigonal/Monoclinic); Cleavage: None; Fracture: Conchoidal; Specific Gravity: 2.6-2.64
Formation & geological history
Formed from the deposition of silica from water at relatively low temperatures, often in volcanic rock cavities or sedimentary fissures. This specimen appears to be a small nodule or seam fragment.
Uses & applications
Used primarily in lapidary arts for decorative carvings, cabochons for jewelry, and as a healing crystal in holistic practices.
Geological facts
Chalcedony is a cryptocrystalline form of silica, meaning its crystals are so small they can only be seen under high magnification. Unlike quartz crystals, its structure is fibrous.
Field identification & locations
Identify by its waxy luster on fractured surfaces and its inability to be scratched by a steel knife. Common in volcanic regions and many riverbeds where silica-rich rocks have weathered.
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