mineral

Moss Agate

Chalcedony (Silicon Dioxide) with dendritic inclusions (SiO2)

AI-generated identification · may be incorrect

Hardness: 6.5-7 Mohs; Color: Clear to milky white with green, black, or brown inclusions; Luster: Vitreous to waxy; Crystal Structure: Hexagonal (cryptocrystalline); Specific Gravity: 2.58–2.64.

Hardness: 6
Color: Clear to milky white with green, black, or brown inclusions
Luster: Vitreous to waxy

Identified April 7, 2026More mineral →

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Physical properties

Hardness: 6.5-7 Mohs; Color: Clear to milky white with green, black, or brown inclusions; Luster: Vitreous to waxy; Crystal Structure: Hexagonal (cryptocrystalline); Specific Gravity: 2.58–2.64.

Formation & geological history

Formed from the deposition of silica-rich groundwater in cavities of igneous rocks. The 'moss' effect is created by the presence of manganese or iron oxides that grow in dendritic (tree-like) patterns as the silica cools.

Uses & applications

Primarily used in jewelry (cabochons, beads, pendants), ornamental carvings, and as a popular specimen for rock collectors.

Geological facts

Despite its name, Moss Agate does not contain organic matter or real moss; the patterns are strictly mineral-based. It has historically been known as the 'gardener's stone' due to folklore claiming it helped crops grow.

Field identification & locations

Identify by looking for translucent chalcedony containing 'branching' green or dark inclusions that resemble underwater plants. It is commonly found in India, Brazil, Uruguay, central Europe, and the western United States.