sedimentary

Dendritic Agate (Blue Chalcedony)

Silicon Dioxide (SiO2)

AI-generated identification · may be incorrect

Hardness: 6.5-7 on Mohs scale; Color: Translucent grey to bluish-white with black/brown inclusions; Luster: Vitreous to waxy; Crystal Structure: Hexagonal (Cryptocrystalline); Cleavage: None/Conchoidal fracture.

Hardness: 6
Color: Translucent grey to bluish-white with black/brown inclusions
Luster: Vitreous to waxy

Identified July 18, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed by the deposition of silica from groundwater in cavities of volcanic rocks or sedimentary formations. The dark patterns are manganese or iron oxide 'pseudo-fossils' that grew during mineral formation.

Uses & applications

Primarily used as a gemstone for jewelry (beads, cabochons), metaphysical healing practices, and as a collector's specimen.

Geological facts

Despite being called 'Dendritic Agate', it is technically a chalcedony because it lacks the concentric banding required to be a true agate. The 'dendrites' are not plant fossils but mineral growths.

Field identification & locations

Identify by its translucent waxy appearance and mossy or tree-like internal inclusions. Often found in riverbeds or gravel deposits in Brazil, India, and the United States (Montana).