mineral

Tumbled banded agate

Agate, microcrystalline quartz (SiO₂), typically chalcedony with iron-oxide inclusions

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; translucent gray, white, orange, and reddish-brown curved banding; waxy to vitreous luster; cryptocrystalline quartz with no visible cleavage and conchoidal fracture. The smoothly polished form is a small tumbled specimen.

Identified September 16, 2026More mineral →

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Physical properties

Formation & geological history

Agate forms when silica-rich groundwater fills cavities in volcanic rock, depositing successive layers of chalcedony and quartz, often with iron staining. Individual specimens may range from Paleozoic to Cenozoic in age, depending on their host rock.

Uses & applications

Used for cabochons, beads, carvings, bookends, decorative objects, and lapidary collections; its toughness makes it suitable for everyday jewelry.

Geological facts

The specimen’s concentric “eye” or fortification bands are characteristic of agate, while the vivid red-orange colors commonly reflect hematite or limonite. Agate is a variety of chalcedony rather than a separate mineral species.

Field identification & locations

Identify it by fine curved or concentric bands, translucency, quartz-like hardness, and inability to scratch with a steel knife easily. Common sources include Brazil, Uruguay, Mexico, India, Madagascar, and the United States.