mineral

Polished agate nodule with druzy center

Banded chalcedony (microcrystalline SiO₂), with quartz crystals lining a cavity

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; pale gray, lavender, and white concentric bands, waxy-to-vitreous luster, and a sparkling crystalline center. The specimen is cut and polished; agate has no visible cleavage and a trigonal quartz structure.

Identified October 12, 2026More mineral →

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Physical properties

Formation & geological history

Silica-rich groundwater deposited successive chalcedony layers in a cavity, later leaving quartz crystals in the central void. Agates form in volcanic and other host rocks over geological time; the image does not reveal a specific age or locality.

Uses & applications

Used as a decorative, collectible specimen and for jewelry or ornamental objects; agate is also used for beads and small carvings.

Geological facts

Agate’s bands record changing conditions during silica deposition; the central sparkle comes from tiny quartz crystals (druzy).

Field identification & locations

Identify by curved concentric bands and a harder, crystalline quartz center. Agates occur worldwide, commonly in volcanic rocks and river gravels; locality cannot be determined from the photo.