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 brown moss-like inclusions; Luster: Vitreous to waxy; Crystal Structure: Trigonal (microcrystalline); Cleavage: None; Specific Gravity: 2.58-2.64

Hardness: 6
Luster: Vitreous to waxy

Identified May 10, 2026More mineral →

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Physical properties

Formation & geological history

Formed from the deposition of silica in volcanic rock cavities or fissures. The dendritic inclusions are formed by the presence of manganese and iron oxides during crystallization. Generally found in Tertiary aged volcanic formations.

Uses & applications

Primarily used in jewelry (cabochons, beads), decorative carvings, and as a popular collector's specimen in polished forms like points/towers.

Geological facts

Despite its name, Moss Agate does not contain organic matter; the 'moss' is actually dendritic mineral inclusions. It was historically favored as a talisman for gardeners and farmers.

Field identification & locations

Identify in the field by its characteristic 'organic' branch-like patterns inside translucent chalcedony. Commonly found in India, Brazil, Uruguay, and the western United States (Montana Moss Agate).

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