mineral

Dendrite (Manganese Oxide Dendrites)

Psilomelane or Pyrolusite on Matrix (typically MnO2)

Hardness: 5-6 (on Mohs scale), Color: Black or dark brown branching patterns on a lighter host rock, Luster: Dull to sub-metallic, Crystal Structure: Monoclinic or Orthorhombic, Cleavage: None visible in dendritic form

Identified January 13, 2026More mineral →

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Physical properties

Formation & geological history

Formed when mineral-rich water (containing manganese or iron) flows through tiny cracks or bedding planes in rocks like limestone, sandstone, or siltstone. As the water evaporates, the minerals precipitate out in a fractal-like, branching pattern. These can form across various geological ages.

Uses & applications

Primarily used as decorative display specimens, in jewelry (often as 'dendritic agate'), and as educational tools to demonstrate branching patterns in nature.

Geological facts

Dendrites are often mistaken for fossilized plants or ferns (pseudofossils) due to their tree-like appearance. The term comes from the Greek word 'dendron,' meaning tree.

Field identification & locations

Identify in the field by looking for flat, dark, moss-like or branch-like patterns that do not possess the cellular structure of real plants. They are commonly found in sedimentary basins and arid environments worldwide. Collectors should check thin fractures in layered rocks.

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Sandstone (with potential mineral staining/concretions)

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