mineral

Moss Agate

Chalcedony (Silicon Dioxide, SiO2) with inclusions

Hardness: 6.5-7 on the Mohs scale, Color: Milky white to translucent with brown, green, or red dendritic inclusions, Luster: Waxy to vitreous, Crystal Structure: Trigonal (cryptocrystalline), Cleavage: None, Specific Gravity: 2.58–2.64

Hardness: 6

Identified January 1, 2026More mineral →

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Physical properties

Formation & geological history

Formed from the deposition of silica-rich groundwater in cavities of igneous rocks. The dendritic patterns are formed by the oxidation of manganese or iron minerals during the cooling process, often spanning millions of years across various geological eras.

Uses & applications

Primarily used as a gemstone for jewelry (cabochons, beads), decorative carvings, and as a collector's specimen. It is also historically used in 'metaphysical' healing practices.

Geological facts

Despite the name, moss agate does not contain organic matter; the 'moss' is actually mineral inclusions. It was historically known as the 'Gardener's Stone' as it was believed to ensure a bountiful harvest.

Field identification & locations

Identify in the field by its translucency and characteristic branch-like or mossy inclusions. Common locations include India, Brazil, Uruguay, and the western United States (Montana). To distinguish from glass, check for the lack of bubbles and its high hardness (it will scratch glass).

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