mineral

Moss Agate

Silicon Dioxide (SiO2) with inclusions of hornblende, chlorite, or manganese/iron oxides

Hardness: 6.5–7 on Mohs scale; Color: Translucent to milky white with green, dendritic (moss-like) or filament-like 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 January 27, 2026More mineral →

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Physical properties

Formation & geological history

Formed through the deposition of silica in cavities of igneous rocks (volcanic basalt). The 'moss' patterns are formed by mineral oxides (such as iron or manganese) entering the silica gel during its cooling and hardening process over millions of years.

Uses & applications

Primarily used in jewelry (cabochons, beads, and pendants), decorative ornaments, and as a popular specimen for collectors. In historical times, it was used as a talisman and for horticultural charms.

Geological facts

Despite its name, Moss Agate does not contain organic plant matter; the 'moss' is purely mineral. It is often referred to as a 'Mocha stone' and has been used throughout history since antiquity, particularly in European jewelry from the 18th century.

Field identification & locations

Identify in the field by looking for a semi-translucent quartz-like stone that contains dark green branching patterns. Common locations include India, Brazil, the United States (specifically Montana), and parts of Central Europe. For collectors, higher translucency and more intricate 'branching' patterns increase value.

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