mineral

Polished banded agate cabochon

Agate, a variety of microcrystalline quartz (SiO₂; chalcedony)

AI-generated identification · may be incorrect

Mohs hardness 6.5–7; translucent gray, cream, and brown bands with a vitreous-to-waxy luster. Trigonal quartz structure; no visible cleavage, conchoidal fracture; specific gravity about 2.6.

Identified October 17, 2026More mineral →

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Physical properties

Mohs hardness 6.5–7; translucent gray, cream, and brown bands with a vitreous-to-waxy luster. Trigonal quartz structure; no visible cleavage, conchoidal fracture; specific gravity about 2.6.

Formation & geological history

Forms as concentric or irregular silica layers lining cavities, commonly in volcanic rocks; banding develops as silica-rich fluids deposit successive layers. Agates form across many geological ages, rather than one specific period.

Uses & applications

Polished cabochons are used in jewelry and collected as ornamental stones; agate is also used for carvings and small decorative objects.

Geological facts

The pictured specimen is cut and polished, revealing characteristic curved chalcedony bands; its exact locality cannot be determined from appearance alone.

Field identification & locations

Identify agate by its fine-grained, translucent silica and distinct curved bands, often visible when backlit. Common sources include Brazil, Uruguay, India, and the United States.