mineral

Tumbled banded agate

Agate, microcrystalline chalcedony (SiO₂)

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; white, cream, gray, and tan concentric bands; waxy to vitreous luster; cryptocrystalline quartz with no visible cleavage and conchoidal fracture. The rounded shape indicates human tumbling/polishing.

Identified September 17, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities in volcanic rock, depositing successive layers of chalcedony and quartz. Individual bands may form over thousands to millions of years; the specimen’s exact age and locality cannot be determined from the image.

Uses & applications

Used for cabochons, beads, carvings, ornaments, paperweights, and lapidary collections; durable agate is also used for burnishing tools and precision surfaces.

Geological facts

The strongly curved, fine banding is characteristic of agate, while the pale coloration suggests low iron content. It may be a variety marketed as Botswana agate or a similar banded chalcedony, but locality identification requires testing or provenance.

Field identification & locations

Identify by its fine curved bands, translucent edges, quartz-like hardness, and absence of cleavage; it commonly occurs in volcanic regions worldwide, especially Brazil, Uruguay, India, Madagascar, and Botswana.