gemstone
Blue Chalcedony (Moonstone-like / Agate)
Silicon Dioxide (SiO2) - Microcrystalline Quartz
Hardness: 6.5-7 on Mohs scale. Color: Translucent sky-blue to lavender-blue with soft adularescence or optical sheen. Luster: Vitreous to waxy. Crystal System: Microcrystalline trigonal.
- Hardness
- 6
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 6.5-7 on Mohs scale. Color: Translucent sky-blue to lavender-blue with soft adularescence or optical sheen. Luster: Vitreous to waxy. Crystal System: Microcrystalline trigonal.
Formation & geological history
Formed through low-temperature precipitation of silica-rich hydrothermal fluids in cavities, volcanic rock pockets, or sedimentary environments.
Uses & applications
Popular gemstone used in jewelry making (rings, pendants, beads) and ornamental carvings due to its pleasing soft blue color and translucency.
Geological facts
Blue chalcedony exhibits a soft internal glow caused by the Tyndall effect—light scattering off fine fibrous inclusions within the quartz matrix. It is sometimes trade-named 'Holly Blue' or 'Blue Lace' depending on banding.
Field identification & locations
Identified by its cryptocrystalline quartz hardness (scratches glass, resists steel), smooth cabochon finish, and distinct translucent pale blue hue. Found globally in Namibia, Turkey, Madagascar, and Brazil.
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