Rock Identifier
Moss Agate (Silicon Dioxide (SiO2) with inclusions of manganese or iron oxides) — Mineral (Variety of Chalcedony)
Mineral (Variety of Chalcedony)

Moss Agate

Silicon Dioxide (SiO2) with inclusions of manganese or iron oxides

Hardness: 6.5–7 on Mohs scale; Color: Clear to milky white with green, dendritic (moss-like) inclusions; Luster: Vitreous to waxy; Crystal structure: Trigonal/Microcrystalline; Cleavage: None; Specific gravity: 2.58–2.64

Hardness
6
Luster
Vitreous to waxy
Identified More mineral (variety of chalcedony) →

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Physical properties

Hardness: 6.5–7 on Mohs scale; Color: Clear to milky white with green, dendritic (moss-like) inclusions; Luster: Vitreous to waxy; Crystal structure: Trigonal/Microcrystalline; Cleavage: None; Specific gravity: 2.58–2.64

Formation & geological history

Formed through the weathering of volcanic rocks. The 'moss' patterns are created when manganese or iron oxides grow in dendritic patterns within the cooling silica gel. It occurs in hydrothermal veins and as nodules in volcanic rock across various geological ages.

Uses & applications

Predominantly used as a gemstone in jewelry (cabochons, beads), decorative carvings, and as a popular specimen for crystal collectors and metaphysical enthusiasts.

Geological facts

Despite its name, moss agate contains no organic plant matter; the green 'moss' is actually mineral impurities. It has been used since ancient times and was historically considered a stone of agriculture, believed by gardeners to ensure a bountiful harvest.

Field identification & locations

Identify in the field by its translucency when held to light, revealing internal branching green filaments. It lacks the banding of true agates. Commonly found in India, Brazil, Uruguay, central Europe, and the western United States (Montana).

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