mineral
Banded agate (likely carnelian or brown agate)
Banded chalcedony, a microcrystalline variety of quartz (SiO₂)
AI-generated identification · may be incorrectDistinct curved bands of reddish-brown, cream, and gray chalcedony; waxy to vitreous luster and no visible cleavage. Hardness is about 6.5–7 Mohs; the small cavity or rough patches may be natural surface features or weathering.
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Physical properties
Distinct curved bands of reddish-brown, cream, and gray chalcedony; waxy to vitreous luster and no visible cleavage. Hardness is about 6.5–7 Mohs; the small cavity or rough patches may be natural surface features or weathering.
Formation & geological history
Silica-rich groundwater deposited successive layers in a cavity, commonly within volcanic rock; the specimen’s age and exact formation setting cannot be determined from the photo.
Uses & applications
Used for beads, cabochons, ornaments, and decorative objects; attractive banding makes it popular with collectors.
Geological facts
Agate’s fine bands form as silica deposits in repeated episodes, producing distinctive curved patterns.
Field identification & locations
The specimen’s banding strongly suggests agate, though a photo cannot confirm its identity or locality. Agates occur worldwide; the reported location in Sergipe, Brazil, is plausible for agate/chalcedony, but the image alone does not establish a local source.
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