Mineral

Dendritic Agate

Silicon Dioxide with Manganese/Iron oxide inclusions (SiO2)

Hardness: 6.5-7 (Mohs scale); Color: Translucent white or gray with dark, tree-like branching inclusions; Luster: Waxy to vitreous; Crystal system: Hexagonal (cryptocrystalline); Specific gravity: 2.60-2.65.

Hardness: 6
Luster: Waxy to vitreous

Identified April 25, 2026More mineral →

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Physical properties

Formation & geological history

Formed when mineral-rich water (carrying manganese or iron) seeps into cracks in chalcedony or volcanic rock, depositing minerals in branching fern-like patterns known as dendrites. These can form in various geological ages inside volcanic host rocks.

Uses & applications

Primarily used as a gemstone for jewelry (cabochons), lapidary art, and as a popular collector's specimen due to its unique patterns.

Geological facts

Although called an agate, it is technically an agate-like chalcedony because it lacks the traditional concentric banding of true agates. The name 'dendrite' comes from the Greek word 'dendron', meaning tree.

Field identification & locations

Identify in the field by its distinctive 'plant-like' patterns that are actually mineral growths, its hardness (it will scratch glass), and its translucent matrix. Common locations include Brazil, India, Madagascar, and the USA (Montana/Kansas).

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Mineral/Rock

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