mineral
Dendritic Opal
Opalized Chalcedony with Manganese Inclusions (SiO2 · nH2O)
AI-generated identification · may be incorrectHardness: 5.5-6.5 on Mohs scale; Color: Milky white to bluish-white with black/brown tree-like inclusions; Luster: Waxy to vitreous; Crystal Structure: Amorphous; Fracture: Conchoidal.
- Hardness
- 5
- Luster
- Waxy to vitreous
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Physical properties
Hardness: 5.5-6.5 on Mohs scale; Color: Milky white to bluish-white with black/brown tree-like inclusions; Luster: Waxy to vitreous; Crystal Structure: Amorphous; Fracture: Conchoidal.
Formation & geological history
Formed when mineral-rich water seeps into cracks in pre-existing rock. The 'dendrites' are formed by manganese or iron oxides crystallizing in branch-like patterns. Common in volcanic regions.
Uses & applications
Primarily used in jewelry (cabochons), ornamental carvings, and as a popular specimen for mineral collectors and metaphysical practitioners.
Geological facts
Despite the name 'Dendritic Opal,' much of what is sold under this name is technically dendritic agate or chalcedony. The branch-like patterns are often mistaken for fossilized plants (ferns), but they are purely inorganic mineral growths.
Field identification & locations
Identify by its characteristic 'milk-and-ink' appearance and lack of 'fire' (opalescence). Common locations include Australia, Mexico, USA, and Madagascar. Collectors look for high contrast and well-defined tree-like patterns.
