Dendritic Agate / Moss Agate

Physical Properties

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

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.

Identified on: 4/19/2026

Mode: Standard