mineral

Moss Agate

Silicon Dioxide (SiO2) with inclusions of manganese or iron oxides

Hardness: 6.5–7 on Mohs scale; Color: Clear to milky white with green, black, or brown moss-like inclusions; Luster: Vitreous to waxy; Crystal structure: Hexagonal (trigonal); Cleavage: None (conchoidal fracture); Specific gravity: 2.58–2.64

Hardness: 6
Luster: Vitreous to waxy

Identified March 15, 2026More mineral →

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Physical properties

Formation & geological history

Formed through the weathering of volcanic rocks, where mineral-rich silica solutions seep into cracks and cavities. The dendritic 'moss' patterns are formed by the crystallization of metallic oxides. It can be found in rocks from various geological eras, including the Cenozoic.

Uses & applications

Primarily used in jewelry (cabochons, beads, pendants), ornamental carvings, and by mineral collectors for its unique aesthetic patterns.

Geological facts

Despite its name, Moss Agate does not contain organic matter; the patterns are strictly mineral-based dendrites. Historically, it was known as the 'Gardener's Stone,' believed to ensure a bountiful harvest.

Field identification & locations

Identify in the field by its translucency against bright light, which reveals the internal dendritic structures. It is commonly found in India, Brazil, Uruguay, and the United States (specifically Montana). Collectors look for high translucency and vivid, well-defined green patterns.

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