mineral

Polished banded agate (likely laguna-style fortification agate)

Microcrystalline quartz, SiO₂; chalcedony with concentric bands

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; golden brown, cream, and gray bands with a waxy-to-vitreous luster; microcrystalline trigonal quartz, with no visible cleavage. The polished face shows concentric fortification patterns.

Identified October 1, 2026More mineral →

Explore Polished banded agate (likely laguna-style fortification agate) in the encyclopedia →

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Physical properties

Formation & geological history

Silica-rich fluids deposited successive chalcedony layers in a cavity, commonly in volcanic rock. Agates formed in many geological periods; this specimen’s exact age and locality cannot be determined from the photo.

Uses & applications

Used for jewelry, cabochons, ornaments, and collecting; agate is also used in decorative objects and small precision components.

Geological facts

Agate’s distinctive bands record repeated mineral deposition, sometimes around a cavity or earlier mineral growth.

Field identification & locations

Look for hard, banded chalcedony that resists scratching by a steel knife and may show translucency at thin edges. Agates occur worldwide, especially in volcanic regions; the image does not establish a specific source.