gemstone

Dendritic agate or included chalcedony (likely tumbled)

Microcrystalline quartz, SiO₂; inclusions likely manganese-oxide dendrites or iron minerals

AI-generated identification · may be incorrect

Translucent cream to pale gray, waxy-to-glassy luster, rounded/tumbled form, with dark branching or speckled inclusions. Quartz hardness is about 7 Mohs; no visible cleavage, cryptocrystalline structure, and specific gravity around 2.6.

Identified September 16, 2026More gemstone →

Explore Dendritic agate or included chalcedony (likely tumbled) in the encyclopedia →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities and fractures in volcanic rock, with later mineral-rich fluids depositing dark dendritic inclusions. The specimen is geologically ancient relative to its host rock, commonly Paleozoic to Cenozoic, though exact age requires locality data.

Uses & applications

Used as a lapidary stone for cabochons, beads, carvings, and inexpensive jewelry; also collected as a decorative specimen.

Geological facts

Dendritic patterns are usually mineral deposits rather than fossils or true crystal branching. Agate is a banded or patterned variety of chalcedony, while similar unbanded material may be called included chalcedony.

Field identification & locations

Identify by testing hardness against glass, observing translucent edges and the waxy surface, and checking that inclusions are internal rather than painted. Common sources include India, Brazil, Uruguay, Mexico, and the United States.