mineral

Dendritic Agate

Silicon Dioxide (SiO2) with inclusions of manganese or iron oxides

Hardness: 6.5-7 Mohs scale; Color: Translucent white to gray with black/brown branching inclusions; Luster: Vitreous to waxy; Crystal structure: Trigonal/Microcrystalline; Cleavage: None (conchoidal fracture); Specific gravity: 2.58-2.64

Hardness: 6
Luster: Vitreous to waxy

Identified March 22, 2026More mineral →

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Physical properties

Formation & geological history

Formed through the deposition of silica-rich groundwater in the cavities of igneous rocks. The 'tree-like' patterns (dendrites) are created when mineral-rich water (manganese or iron) seeps into cracks during the stone's formation.

Uses & applications

Commonly used in lapidary work for cabochons, jewelry, and ornamental carvings. It is high-value for collectors who appreciate 'landscape' patterns.

Geological facts

Despite the name 'Dendritic Agate,' it is technically a chalcedony because it lacks the concentric banding of true agates. The term 'dendrite' comes from the Greek word 'dendron,' meaning tree.

Field identification & locations

Identify in the field by its translucency and characteristic black/brown plant-like patterns that do not rub off. Commonly found in Brazil, India, Madagascar, and the USA (notably Montana and Nebraska).

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