mineral

Moss Agate

Chalcedony (SiO2) with inclusions of manganese or iron oxides

Hardness: 6.5-7 (Mohs). Color: Clear to milky white with green, black, or red dendritic inclusions. Luster: Vitreous to waxy. Crystal Structure: Trigonal (microcrystalline). Cleavage: None. SG: 2.58-2.64.

Hardness: 6
Luster: Vitreous to waxy

Identified April 18, 2026More mineral →

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Physical properties

Formation & geological history

Formed from the deposition of silica-rich groundwater in the cavities of igneous rocks. The 'moss' patterns are caused by dendritic inclusions of metal oxides that crystallize as the silica solidifies.

Uses & applications

Primarily used in jewelry (cabochons, beads), ornamental carvings, and as a popular lapidary material for collectors.

Geological facts

Despite its name, Moss Agate does not contain organic matter or moss. It was historically regarded as a stone of agriculture, and gardeners believed it would ensure a bountiful harvest.

Field identification & locations

Identify by looking for translucent to transparent chalcedony with branch-like, mossy, or filamentous patterns. Commonly found in India, Brazil, Uruguay, and the United States (Montana).

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Mineral/Rock

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Metamorphic Rock

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