mineral

Moss Agate

Cryptocrystalline Quartz (SiO2 with manganese or iron oxide inclusions)

Hardness: 6.5-7 on Mohs scale; Color: Clear to milky base 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 23, 2026More mineral →

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Physical properties

Formation & geological history

Formed in cavities of volcanic rocks or limestone through the deposition of silica from hydrothermal fluids. The 'moss' patterns are formed by dendritic inclusions of manganese or iron oxides during crystallization.

Uses & applications

Primarily used in jewelry making (cabochons, rings), ornamental carvings, and by crystal collectors for its aesthetic patterns.

Geological facts

Despite its name, moss agate is not organic and contains no actual moss. It is sometimes called the 'Mocha Stone' after the city of Mocha in Yemen, once a source of the stone.

Field identification & locations

Identified by its distinctive dendritic or moss-like inclusions within a translucent chalcedony host. It is commonly found in India, Brazil, Uruguay, and the United States (Montana). Collectors look for high transparency and vivid, complex patterns.

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