mineral

Polished dendritic agate (likely moss or plume agate)

Microcrystalline quartz, SiO₂, with iron-oxide inclusions

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; translucent milky-gray chalcedony with blue-gray banding and tan-to-gold iron-oxide or mineral inclusions. Waxy to glassy luster, cryptocrystalline structure, no visible cleavage, and specific gravity about 2.6.

Identified September 20, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities in volcanic rocks, depositing chalcedony in layers; later fluids create branching inclusions and iron staining. Agates generally formed during volcanic activity from the Paleozoic to Cenozoic eras.

Uses & applications

Used for cabochons, carvings, beads, ornamental slabs, and collector specimens; durable enough for minor decorative and lapidary applications.

Geological facts

The apparent gold patterns are usually iron oxides or other mineral inclusions rather than native gold. Polishing enhances translucency, banding, and contrast.

Field identification & locations

Identify by translucent chalcedony, curved internal banding, waxy luster, and hardness sufficient to scratch glass. Common sources include Brazil, Uruguay, Mexico, India, Madagascar, and the western United States.