gemstone

Polished green banded agate

Chalcedony (microcrystalline quartz), SiO₂; likely moss or green banded agate

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; translucent dark green to gray-green with curved black and pale bands, waxy-to-glassy luster, and no visible cleavage. The smooth domed surface indicates a polished cabochon or tumbled specimen.

Identified September 17, 2026More gemstone →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities in volcanic rock, depositing layers of chalcedony and included minerals over time. Agates commonly formed during the Paleozoic–Cenozoic, though the specimen’s exact age and locality cannot be determined visually.

Uses & applications

Used for cabochons, pendants, carvings, beads, and ornamental objects; also collected for its attractive banding.

Geological facts

Green coloration may result from chlorite, epidote, or other inclusions, while dark bands are typically iron- or manganese-bearing layers. Agate’s concentric or curved banding reflects repeated silica deposition.

Field identification & locations

Identify by its translucency, curved natural banding, glassy/waxy polish, and quartz-like hardness; common sources include Brazil, Uruguay, India, Madagascar, and the western United States.