mineral

Polished banded agate

Microcrystalline quartz (chalcedony), SiO₂, with iron-oxide coloring

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; waxy to vitreous luster, opaque gray, cream, and orange-brown bands. Trigonal quartz in microscopic fibers; no visible cleavage, conchoidal fracture; exact properties depend on the specimen.

Identified September 23, 2026More mineral →

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Physical properties

Formation & geological history

Silica-rich fluids deposited successive chalcedony layers in a cavity or fracture, with iron oxides producing the warm colors. Agates form in many volcanic and sedimentary settings across geologic time.

Uses & applications

Used for jewelry, ornaments, carvings, and collectibles; agate is also used for small precision components and traditional decorative objects.

Geological facts

Agate’s distinctive bands record changing conditions during mineral deposition; polishing reveals patterns that may be subtle on a rough surface.

Field identification & locations

Identify by curved or irregular concentric bands, waxy luster, and hardness sufficient to scratch glass; the image shows a polished, irregular banded specimen. Agates occur worldwide, including Brazil, Uruguay, India, and the western United States.