mineral
Tumbled agate/chalcedony (likely moss or plume agate)
Microcrystalline quartz, SiO₂, chiefly chalcedony with possible iron-oxide inclusions
AI-generated identification · may be incorrectHardness 6.5–7 Mohs; translucent cream, gray, brown, and bluish colors with cloudy or faintly banded internal patterns; waxy to vitreous luster and no cleavage. The smoothly rounded shape indicates tumbling and polishing.
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Physical properties
Hardness 6.5–7 Mohs; translucent cream, gray, brown, and bluish colors with cloudy or faintly banded internal patterns; waxy to vitreous luster and no cleavage. The smoothly rounded shape indicates tumbling and polishing.
Formation & geological history
Forms when silica-rich groundwater fills cavities in volcanic rocks, depositing chalcedony and quartz in layers around inclusions over long periods, commonly during the Cenozoic or older volcanic episodes.
Uses & applications
Used for inexpensive cabochons, beads, carvings, ornaments, and lapidary collections; durable enough for some small decorative objects.
Geological facts
Agate is a variety of chalcedony distinguished by banding, color zoning, or inclusion patterns; exact identification from a photograph is limited because similar jasper and common chalcedony can look alike.
Field identification & locations
Common sources include Brazil, Uruguay, Mexico, India, Madagascar, and the western United States. Look for translucency, waxy luster, curved banding, and conchoidal fracture; a streak test is white, and it should resist scratching by steel.
