mineral

Moss Agate

Silicon Dioxide with inclusions (SiO2)

Hardness: 6.5-7 (Mohs); Color: Green, white, clear with dendritic inclusions; Luster: Vitreous to waxy; Crystal structure: Trigonal (cryptocrystalline); Specific gravity: 2.58-2.64

Hardness: 6
Color: Green, white, clear with dendritic inclusions
Luster: Vitreous to waxy

Identified April 7, 2026More mineral →

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Physical properties

Hardness: 6.5-7 (Mohs); Color: Green, white, clear with dendritic inclusions; Luster: Vitreous to waxy; Crystal structure: Trigonal (cryptocrystalline); Specific gravity: 2.58-2.64

Formation & geological history

Formed from the weathering of volcanic rocks where silica-rich groundwater fills cavities and precipitates out. The 'moss' patterns are caused by impurities of manganese or iron oxides during formation.

Uses & applications

Used primarily in lapidary arts for jewelry, decorative carvings (like the arrowhead shapes shown), and as a popular collector's specimen.

Geological facts

Despite its name, moss agate does not contain organic plant matter; the green patterns are purely mineral-based dendrites. It is often referred to as the 'Mocha stone'.

Field identification & locations

Identify by its translucent body combined with dark green, branch-like or moss-like inclusions. Commonly found in India, Brazil, and the USA (notably Montana). It is a staple for rockhounds due to its unique patterns.