mineral

Moss Agate

Silicon Dioxide (SiO2) with inclusions

Hardness: 6.5–7 on Mohs scale; Color: Clear or milky white with green, dendritic inclusions; Luster: Vitreous to waxy; Crystal Structure: Hexagonal (trigonal), microcrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.58–2.64.

Hardness: 6
Color: Clear or milky white with green, dendritic inclusions
Luster: Vitreous to waxy

Identified March 24, 2026More mineral →

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Physical properties

Formation & geological history

Formed through the deposition of silica from groundwater in cavities of igneous rocks. The 'moss' appearance is caused by manganese or iron oxide inclusions that form dendritic patterns. These can range from millions to hundreds of millions of years old depending on the host rock formation.

Uses & applications

Primarily used as a gemstone in jewelry (cabochons, beads), decorative carvings, and as a popular specimen for rock collectors and metaphysical practitioners.

Geological facts

Despite its name, moss agate does not contain organic matter; the mossy patterns are strictly mineral-based. It was historically viewed as a stone of agriculture and gardeners, believed to help crops flourish.

Field identification & locations

Identify in the field by its translucent body combined with dark green or black filament-like patterns. Common locations include India, Brazil, Uruguay, and the United States (specifically the Yellowstone River area). It is often found as river-worn pebbles or within volcanic rock vugs.