mineral

Polished chalcedony (likely moss or dendritic agate)

Microcrystalline quartz, SiO₂, with iron/manganese oxide inclusions

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; translucent milky-white to gray with brown-black dendritic inclusions, waxy luster, cryptocrystalline structure, and no visible cleavage. The smoothly rounded surface indicates tumbling or polishing.

Identified August 14, 2026More mineral →

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Physical properties

Formation & geological history

Silica-rich groundwater deposited chalcedony in cavities or fractures, while metal oxides formed branching inclusions during growth; most specimens are Cenozoic or older. Common sources include Brazil, India, Uruguay, Madagascar, and the western United States.

Uses & applications

Used for cabochons, beads, carvings, ornamental objects, and lapidary collections; not generally used as a construction stone in this small form.

Geological facts

Dendritic patterns are mineral-growth inclusions, not fossils or plant material. Chalcedony is a cryptocrystalline variety of quartz and includes agate, jasper, and onyx varieties.

Field identification & locations

Identify by its waxy luster, translucent edges, glassy hardness, and lack of cleavage; it should scratch glass but not be scratched by a steel knife. A definitive identification may require microscopy or spectroscopy.