mineral

Dendritic Agate

Chalcedony (Silicon Dioxide, SiO2) with Manganese/Iron oxide inclusions

Hardness: 6.5-7 (Mohs scale), Color: White or translucent gray with black or brown tree-like branch patterns, Luster: Waxy to vitreous, Crystal Structure: Hexagonal (cryptocrystalline), Cleavage: None (conchoidal fracture), Specific Gravity: 2.58-2.64

Hardness: 6

Identified July 19, 2026More mineral →

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Physical properties

Formation & geological history

Forms primarily in cavities of volcanic rocks or sedimentary environments where groundwater rich in silica and manganese/iron oxides flows into cracks, crystallizing over millions of years. The 'dendrites' are formed by the fractal crystallization of manganese or iron minerals.

Uses & applications

Used extensively in jewelry as cabochons, as ornamental stones, and in crystal healing/collecting. Historically used for talismans.

Geological facts

The name 'dendrite' comes from the Greek word 'dendron' meaning 'tree'. Despite its name, it is technically an agate, though it often lacks the classic concentric banding found in other agates.

Field identification & locations

Identify by the presence of dark, fern-like or moss-like inclusions against a milky white or translucent quartz base. Commonly found in Brazil, India, Madagascar, and the USA (Montana). Collectors look for high contrast and clear dendritic patterns.

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