mineral

Tree Agate

Dendritic Agate (Silicon Dioxide, SiO2)

Hardness: 6.5–7 on Mohs scale. Color: White or milky base with dark green branching inclusions. Luster: Waxy to vitreous. Crystal Structure: Hexagonal (Trigonal), cryptocrystalline. Cleavage: None (conchoidal fracture). Specific Gravity: 2.58–2.64.

Hardness: 6
Color: White or milky base with dark green branching inclusions
Luster: Waxy to vitreous

Identified March 22, 2026More mineral →

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Physical properties

Formation & geological history

Formed through the cooling of silica-rich groundwater in the cavities of igneous or sedimentary rocks. The 'tree-like' patterns are manganese or iron oxide dendrites that seeped into fractures during formation. They can be found in formations ranging from the Cenozoic to much older eras.

Uses & applications

Primarily used as a gemstone for jewelry (cabochons, beads, pendants), decorative carvings, and in metaphysical rock collecting. It is also used as an ornamental stone in polished form.

Geological facts

Despite being called 'Tree Agate', it is technically a dendritic chalcedony because it lacks the concentric banding required to be a 'true agate'. The name comes from the Greek word 'dendron' meaning tree. Ancient Greeks believed it could ensure a bountiful harvest.

Field identification & locations

Identify in the field by its distinct white-and-green 'mossy' or 'branching' appearance and its high hardness (it will scratch glass). Commonly found in Brazil, India, Uruguay, and parts of the United States like Montana.