mineral

Moss Agate

Silicon Dioxide with inclusions (SiO2)

Hardness: 6.5 - 7 on Mohs scale. Color: Translucent to milky white chalcedony quartz with dark green, moss-like inclusions of chlorite, hornblende, or iron/manganese minerals. Luster: Waxy to vitreous. Crystal system: Microcrystalline (trigonal). Cleavage: None, exhibits conchoidal fracture.

Hardness: 6
Luster: Waxy to vitreous

Identified July 22, 2026More mineral →

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Physical properties

Formation & geological history

Formed as a secondary mineral in volcanic host rocks (basalts and andesites) where silica-rich hydrothermal fluids precipitate in cavities along with iron, manganese, or chlorite minerals that create the characteristic dendrites.

Uses & applications

Popular in jewelry (cabochons, beads, pendants), ornamental carvings, polished display slabs, and lapidary crafts.

Geological facts

Despite its name, moss agate is not a true agate because it lacks concentric banding, and the moss-like patterns are mineral inclusions, not organic plant matter.

Field identification & locations

Look for translucent chalcedony quartz filled with deep green, plant-like branching inclusions. Commonly found in India, Brazil, Montana (USA), Uruguay, and Madagascar.