Moss Agate

Physical Properties

Hardness: 6.5–7 on Mohs scale; Color: Clear to milky white base with green or brown dendritic patterns; Luster: Vitreous to waxy; Crystal Structure: Trigonal (microcrystalline); Specific Gravity: 2.58–2.64.

Formation & Geological History

Formed from the deposition of silica-rich groundwater in cavities of igneous rocks. The 'moss' patterns are caused by impurities of manganese or iron oxides that form dendritic patterns during crystallization.

Uses & Applications

Primarily used in jewelry (cabochons), lapidary carvings, and as a collector's specimen. It is also popular in holistic and metaphysical communities.

Geological Facts

Despite its name, moss agate does not contain organic plant matter; the 'moss' is purely mineral growth. It is often called the 'Mocha Stone' after the city of Mocha in Yemen, an early trade source.

Field Identification & Locations

Identify by its translucent body combined with branching, moss-like inclusions. It is commonly found in India, Brazil, Uruguay, and the United States (notably Montana). For collectors, look for high transparency and vibrant green 'moss'.

Identified on: 4/29/2026

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