mineral

Polished banded agate

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

AI-generated identification · may be incorrect

Mohs hardness 6.5–7; tan, cream, and honey-brown bands with a waxy to vitreous luster and no visible cleavage. It appears shaped and polished; its precise crystal structure is microscopic quartz fibers.

Identified September 23, 2026More mineral →

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Physical properties

Formation & geological history

Forms as silica-rich fluids deposit successive layers in cavities, commonly in volcanic rocks. Agate occurs in rocks of many ages, so the specimen’s age cannot be determined from the image.

Uses & applications

Used for jewelry, carvings, ornaments, and decorative objects; its hardness makes it suitable for durable polished pieces.

Geological facts

Agate’s contrasting bands record changes in the chemistry or conditions of silica deposition.

Field identification & locations

Identify by curved or irregular color bands and a smooth, hard surface; common sources include Brazil, Uruguay, India, and the United States. The pictured specimen is likely a polished carving or tumble.