mineral

Tumbled tree agate (dendritic agate)

Cryptocrystalline quartz, SiO₂, with manganese/iron-oxide dendrites

AI-generated identification · may be incorrect

White to pale gray, opaque chalcedony with dark green-black branching inclusions; waxy to vitreous luster and no visible cleavage. Mohs hardness 6.5–7; typically microcrystalline quartz with specific gravity around 2.6.

Identified August 8, 2026More mineral →

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Physical properties

Formation & geological history

Silica-rich groundwater filled cavities and fractures in volcanic rock, while manganese or iron-bearing fluids formed the fern-like dendrites. Most commercial material is Cenozoic to older volcanic-hosted chalcedony, then polished by tumbling.

Uses & applications

Used as an inexpensive cabochon, bead, worry stone, and decorative specimen; rarely used industrially because pieces are small.

Geological facts

The branching patterns are mineral inclusions, not fossil plants. It is often marketed as “tree agate,” though true tree agate commonly has green inclusions in a white chalcedony matrix.

Field identification & locations

Identify it by its smooth tumbled shape, waxy white chalcedony body, and natural branching inclusions; glass usually has bubbles and greater uniformity. Common sources include India, Brazil, Madagascar, and the western United States.