mineral

Moss Agate

Chalcedony (SiO2) with inclusions of hornblende or chlorite

Hardness: 6.5–7 (Mohs scale); Color: Clear to milky white with green, black, or red dendritic patterns; Luster: Vitreous to waxy; Crystal structure: Trigonal/Microcrystalline; Cleavage: None; 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 deposition of silica in volcanic rock cavities or veins. The 'moss' patterns are formed by dendritic inclusions of manganese or iron oxides/silicates. They can range from the Precambrian era to more recent volcanic activity.

Uses & applications

Primarily used in jewelry (cabochons, beads), decorative carvings, and as a popular collector's mineral due to its unique organic appearance.

Geological facts

Despite its name, moss agate is not a true agate because it lacks the distinctive concentric banding. It is technically a variety of chalcedony. In ancient times, it was considered a lucky stone for gardeners and farmers.

Field identification & locations

Identify by its translucent body combined with dark green or black filaments that resemble moss. Commonly found in India, Brazil, Uruguay, and the United States (notably Montana). Collectors should look for high transparency and vivid 'leafy' patterns.

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