mineral

Banded Agate (Polished Slice)

Chalcedony (SiO2) with Quartz

AI-generated identification · may be incorrect

Hardness: 6.5-7 Mohs; Color: Brown, tan, cream, and white banding; Luster: Waxy to vitreous when polished; Structure: Cryptocrystalline; Cleavage: None (Conchoidal fracture)

Hardness: 6
Color: Brown, tan, cream, and white banding
Luster: Waxy to vitreous when polished

Identified July 3, 2026More mineral →

Explore Banded Agate (Polished Slice) in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Hardness: 6.5-7 Mohs; Color: Brown, tan, cream, and white banding; Luster: Waxy to vitreous when polished; Structure: Cryptocrystalline; Cleavage: None (Conchoidal fracture)

Formation & geological history

Formed through the deposition of silica from groundwater in the cavities of igneous rocks, primarily volcanic lavas. The banding occurs due to rhythmic crystallization or changes in the chemical composition of the silica-rich fluids over time.

Uses & applications

Used widely in ornamental carvings, jewelry (cabochons), interior decor (coasters, bookends), and historically for precision instruments like mortars and pestles.

Geological facts

Agate is a variety of chalcedony, which is a microcrystalline form of quartz. The distinctive banding is its most identifying feature, and individual patterns are unique to each specimen. It was named by Theophrastus after the Achates River in Sicily.

Field identification & locations

Identify by its translucent nature when held to light and its characteristic concentric or planar banding. Commonly found in Brazil, Uruguay, and various locations across the United States. Collectors look for sharp contrast in bands and lack of fractures.