mineral

Polished banded agate

Microcrystalline quartz (SiO₂), chiefly chalcedony

AI-generated identification · may be incorrect

Mohs hardness 6.5–7; glossy polish and curved brown, cream, and gray bands. Trigonal quartz structure at microscopic scale; no visible cleavage, conchoidal fracture; specific gravity about 2.6.

Identified September 26, 2026More mineral →

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Physical properties

Mohs hardness 6.5–7; glossy polish and curved brown, cream, and gray bands. Trigonal quartz structure at microscopic scale; no visible cleavage, conchoidal fracture; specific gravity about 2.6.

Formation & geological history

Silica-rich groundwater deposited successive layers of chalcedony in a cavity, commonly in volcanic rock; banding formed during repeated changes in fluid chemistry. The specimen’s precise age and locality cannot be determined from the image.

Uses & applications

Used for jewelry, cabochons, ornaments, and lapidary collections; agate is also used for small precision components.

Geological facts

Agate is a banded variety of chalcedony, and its distinctive layers are revealed by cutting and polishing.

Field identification & locations

Identify by its waxy-to-glassy luster, hardness, and fine, often curved bands; common sources include Brazil, Uruguay, India, and the western United States. This appears to be a shaped, polished specimen.