mineral

Polished chalcedony (likely moss or dendritic agate)

Microcrystalline quartz, SiO₂; chalcedony with possible iron-oxide inclusions

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; waxy to vitreous luster; pale gray, cream, tan, and translucent zones with brown internal inclusions. Quartz has a trigonal structure but chalcedony is cryptocrystalline, with no visible cleavage and conchoidal fracture.

Identified September 15, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities and fractures in volcanic rocks, commonly during the Cenozoic or older volcanic episodes; iron and manganese oxides create the cloudy or moss-like patterns.

Uses & applications

Used for cabochons, beads, carvings, and ornamental objects; also collected as an attractive lapidary stone.

Geological facts

The smooth surface indicates human polishing, while the cloudy translucence and earthy inclusions are typical of chalcedony or agate rather than ordinary glass.

Field identification & locations

Identify by its cool feel, glassy/waxy luster, translucence, lack of cleavage, and hardness sufficient to scratch ordinary glass. Common sources include Brazil, India, Madagascar, Uruguay, and the western United States.