Rock Identifier

mineral

Dendritic Agate or Merlinite (Polished Cabochon)

Silicon dioxide with manganese or iron oxide inclusions (SiO2)

AI-generated identification · may be incorrect

Hardness of 6.5-7 on the Mohs scale, typically white or gray base color with black or dark gray branching/moss-like (dendritic) inclusions. Luster is vitreous to waxy when polished. Cryptocrystalline structure.

Identified August 16, 2026More mineral →

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Physical properties

Hardness of 6.5-7 on the Mohs scale, typically white or gray base color with black or dark gray branching/moss-like (dendritic) inclusions. Luster is vitreous to waxy when polished. Cryptocrystalline structure.

Formation & geological history

Formed in cavities of volcanic rocks or associated with hot springs. The dendrites are formed by manganese or iron oxides crystallizing within fractures in the chalcedony.

Uses & applications

Commonly cut and polished into cabochons for jewelry, such as pendants. Also collected for its unique patterns.

Geological facts

Dendritic agate is often called the 'tree stone' because its inclusions look like ferns or branches, though they are entirely inorganic.

Field identification & locations

Identified by its contrasting dark, branching patterns against a lighter chalcedony background. Found in places like India, Brazil, and the USA.

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