mineral

Dendritic Agate / Moss Agate

Silicon Dioxide (SiO2) with Manganese/Iron oxide inclusions

Hardness: 6.5-7 (Mohs); Color: Translucent grey to white with dark inclusions; Luster: Vitreous to waxy; Crystal Structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific Gravity: 2.58–2.64

Hardness: 6
Color: Translucent grey to white with dark inclusions
Luster: Vitreous to waxy

Identified April 19, 2026More mineral →

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Physical properties

Formation & geological history

Formed in cavities within volcanic or sedimentary rocks through the deposition of silica-rich groundwater. The tree-like or spotted inclusions are formed by the infiltration of manganese or iron oxides during crystallization.

Uses & applications

Used primarily for jewelry making (cabochons), collection, decorative carvings, and alternative healing practices.

Geological facts

Despite the name, moss or dendritic agates do not contain organic matter; the 'plant' patterns are purely mineral growth called dendrites. They were historically known as 'The Gardner's Stone' for their alleged ability to ensure a good harvest.

Field identification & locations

Identify in the field by its translucency (light passes through edges) and the presence of internal moss-like or speckled patterns that do not rub off. Common in riverbeds and volcanic regions like those in Montana, USA, or India.

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