mineral

Moss Agate

Chalcedony (SiO2) with inclusions of manganese or iron oxide

Hardness: 6.5-7 (Mohs scale); Color: Clear to white base with green, black, or brown dendritic inclusions; Luster: Vitreous to waxy; Crystal structure: Trigonal (microcrystalline); Cleavage: None; Specific Gravity: 2.58-2.64

Hardness: 6
Luster: Vitreous to waxy

Identified March 18, 2026More mineral →

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Physical properties

Formation & geological history

Formed through the weathering of volcanic rocks and the deposition of silica-rich groundwater. The moss-like patterns are caused by dendritic inclusions of minerals like manganese, chrome, or iron that grow into the cooling silica gel.

Uses & applications

Primary use is in jewelry (cabochons, beads), decorative carvings, and as a popular specimen for metaphysical crystal collecting.

Geological facts

Despite its name, moss agate does not contain organic plant matter; the 'moss' is purely mineral. It has been used since ancient times as a talisman for gardeners and a stone of fertility.

Field identification & locations

Identify in the field by its characteristic 'veined' or 'mossy' filaments inside semi-translucent chalcedony. It is commonly found in India, Brazil, the US (Montana), and Uruguay. It will not scratch with a knife but can scratch glass.

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Mineral

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Mineral/Rock

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