mineral
Tumbled agate (likely)
Microcrystalline quartz, SiO₂; agate is banded chalcedony
AI-generated identification · may be incorrectPolished, rounded gray-brown stone with cloudy, mottled coloration and a waxy-to-glassy luster. Quartz hardness is 7 Mohs; trigonal crystal structure, but crystals are microscopic, with no distinct cleavage and conchoidal fracture.
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Physical properties
Polished, rounded gray-brown stone with cloudy, mottled coloration and a waxy-to-glassy luster. Quartz hardness is 7 Mohs; trigonal crystal structure, but crystals are microscopic, with no distinct cleavage and conchoidal fracture.
Formation & geological history
Forms as silica-rich groundwater fills cavities in volcanic rock, depositing layers of chalcedony over time. The image cannot establish its precise age or locality.
Uses & applications
Used for lapidary work, jewelry, ornaments, and collecting; agate is also used for small decorative and industrial objects.
Geological facts
Agate is a variety of chalcedony and may show distinct bands when cut; this specimen’s exterior does not reveal clear banding.
Field identification & locations
The rounded shape and glossy finish indicate tumbling or polishing. Confirm agate by inspecting a cut face for fine bands; similar opaque chalcedony is common worldwide, especially in volcanic regions.
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