mineral
Botryoidal Chalcedony / Quartz
Silicon Dioxide (SiO2)
Hardness of 7 on the Mohs scale; color ranges from tan, brown, to honey-yellow; luster is vitreous to waxy; crystal structure is microcrystalline/cryptocrystalline quartz (trigonal); fracture is conchoidal; specific gravity is 2.60 to 2.65.
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Physical properties
Hardness of 7 on the Mohs scale; color ranges from tan, brown, to honey-yellow; luster is vitreous to waxy; crystal structure is microcrystalline/cryptocrystalline quartz (trigonal); fracture is conchoidal; specific gravity is 2.60 to 2.65.
Formation & geological history
Formed via low-temperature deposition from silica-rich hydrothermal solutions or groundwater circulating through cavities in volcanic or sedimentary rocks, often developing a botryoidal (grape-like) habit due to surface tension during precipitation.
Uses & applications
Used primarily as a lapidary material for cabochons, carvings, ornamental objects, and collected by mineral enthusiasts.
Geological facts
The characteristic grape-like or bubbly shape forms when many tiny quartz crystals grow outward from central points simultaneously, merging together in solution.
Field identification & locations
Found worldwide in cavities of basalt and limestone, often identified by its smooth, rounded, bulbous surface texture and conchoidal fracture.
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