Dendritic Moss Agate

Physical Properties

Hardness: 6.5–7 (Mohs scale); Color: Translucent blue-grey with yellow/green moss-like inclusions; Luster: Waxy to vitreous; Crystal Structure: Trigonal (Microcrystalline); Specific Gravity: 2.58–2.64.

Formation & Geological History

Formed from the deposition of silica from groundwater in cavities of igneous rocks. The 'moss' inclusions are typically manganese or iron oxides that form dendritic patterns during the cooling and solidification process.

Uses & Applications

Primarily used for ornamental purposes, tumbling, lapidary arts, jewelry (cabochons), and as a collector's specimen.

Geological Facts

Despite its name, moss agate is not a true 'agate' because it lacks the concentric banding of true agates; it is technically a variety of chalcedony. The yellow inclusions in this specific piece are likely caused by iron oxides (limonite).

Field Identification & Locations

Identify in the field by its waxy luster, translucency, and the presence of branch-like or moss-like organic patterns inside the stone. Commonly found in India, Brazil, and the USA (notably Montana).

Identified on: 4/13/2026

Mode: Standard