mineral
Blue Chalcedony Geode
Silicon Dioxide (SiO2)
AI-generated identification · may be incorrectHardness: 6.5-7 Mohs; Color: Pale blue to milky grey; Luster: Waxy to vitreous; Crystal structure: Trigonal/Monoclinic (Cryptocrystalline); Cleavage: None; Specific Gravity: 2.58-2.64
- Hardness
- 6
- Color
- Pale blue to milky grey
- Luster
- Waxy to vitreous
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Physical properties
Hardness: 6.5-7 Mohs; Color: Pale blue to milky grey; Luster: Waxy to vitreous; Crystal structure: Trigonal/Monoclinic (Cryptocrystalline); Cleavage: None; Specific Gravity: 2.58-2.64
Formation & geological history
Formed through the deposition of silica-rich fluids in volcanic cavities or sedimentary pockets. Over millions of years, microcrystalline quartz layers build up from the walls inward. Found in basaltic or rhyolitic host rocks.
Uses & applications
Used primarily in lapidary arts, jewelry, decorative ornaments, and as meditation stones in alternative healing practices.
Geological facts
Chalcedony is a cryptocrystalline form of silica, meaning its crystals are too small to be seen with a standard microscope. Blue varieties are particularly prized for their ethereal glow caused by the Tyndall effect.
Field identification & locations
Identify by its waxy luster on the face and the rough, cauliflower-like texture of its outer 'rind'. Check for translucency under a bright light source. Common locations include Brazil, Malawi, and Namibia.
