mineral

Moss Agate

Silicon Dioxide (SiO2) with inclusions of hornblende or chlorite

Hardness: 6.5–7 (Mohs scale); Color: Clear or milky white with green, black, or red dendritic inclusions; Luster: Vitreous to waxy; Crystal Structure: Trigonal/Microcrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.58–2.64

Hardness: 6
Luster: Vitreous to waxy

Identified March 28, 2026More mineral →

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Physical properties

Formation & geological history

Formed through the cooling of silica-rich groundwater in the fissures and cavities of volcanic rocks (basalts). The 'moss' patterns are formed by dendritic inclusions of manganese and iron oxides or chlorite that crystalized early in the agate formation.

Uses & applications

Used primarily in jewelry (cabochons, beads, rings), as a decorative ornamental stone, and in metaphysical collecting. Historically used by farmers as a 'talisman' for good harvests.

Geological facts

Despite its name, moss agate does not contain organic matter or real moss; the patterns are strictly mineral. It is often called the 'Mocha Stone' after the Arabian city of Mocha where it was once traded extensively.

Field identification & locations

Identify in the field by its translucent body combined with dark, leafy inclusions that resemble vegetation. Commonly found in India, Brazil, Uruguay, and the western United States (Montana). Tips for collectors: look for high transparency in the base stone to highlight the pattern.

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