mineral
Chalcedony
Silicon Dioxide (SiO2)
Hardness: 6.5-7 on the Mohs scale, Color: Various shades of blue, grey, white, or multicolored, Luster: Waxy to vitreous, Crystal structure: Trigonal (microcrystalline quartz/moganite mixture), Cleavage: None, Specific gravity: 2.58-2.64
- Hardness
- 6
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Physical properties
Hardness: 6.5-7 on the Mohs scale, Color: Various shades of blue, grey, white, or multicolored, Luster: Waxy to vitreous, Crystal structure: Trigonal (microcrystalline quartz/moganite mixture), Cleavage: None, Specific gravity: 2.58-2.64
Formation & geological history
Forms in low-temperature hydrothermal environments, filling cavities in volcanic or sedimentary rocks through the deposition of silica-rich solutions over millions of years.
Uses & applications
Used in ornamental carvings, lapidary arts, jewelry, and as a collectible mineral specimen.
Geological facts
Chalcedony has been used since antiquity to create intaglios, seals, and precious gemstones due to its fine grain and durability.
Field identification & locations
Can be identified by its distinctive waxy luster, microcrystalline texture, and botryoidal or crusting habit lining cavities. Commonly found worldwide in volcanic rock vesicles.
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