Rock Identifier
Dendritic Agate (Tumbled) (Silicon Dioxide (SiO2) with inclusions) — mineral
mineral

Dendritic Agate (Tumbled)

Silicon Dioxide (SiO2) with inclusions

Hardness: 6.5-7 on the Mohs scale. Color: White or grayish-translucent with tree-like inclusions. Luster: Vitreous to waxy. Crystal Structure: Hexagonal (cryptocrystalline). Cleavage: None (conchoidal fracture). Specific Gravity: 2.58–2.64.

Hardness
6
Color
White or grayish-translucent with tree-like inclusions
Luster
Vitreous to waxy
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Physical properties

Hardness: 6.5-7 on the Mohs scale. Color: White or grayish-translucent with tree-like inclusions. Luster: Vitreous to waxy. Crystal Structure: Hexagonal (cryptocrystalline). Cleavage: None (conchoidal fracture). Specific Gravity: 2.58–2.64.

Formation & geological history

Formed through the deposition of silica from groundwater in cavities of igneous rocks. The 'tree-like' markings (dendrites) are created by manganese or iron oxides crystallizing in a branching pattern. They occur in various geological ages ranging from the Cretaceous to the Recent.

Uses & applications

Used primarily in lapidary work for jewelry (cabochons, beads), decorative carvings, and as a popular specimen for crystal collecting and metaphysical practices.

Geological facts

Despite the name, Agate is technically a variety of chalcedony. The 'dendrites' are often mistaken for fossilized plants or moss, but they are purely inorganic mineral growth (manganese/iron oxide). It is often called the 'Stone of Plenitude'.

Field identification & locations

Identify in the field by its translucent white/milky body and dark, fern-like inclusions. It is commonly found in Brazil, India, Madagascar, and parts of the United States (such as Montana and Oregon). It can be identified by its inability to be scratched by a steel knife.

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