Dendritic Agate
Image: <a href="//commons.wikimedia.org/wiki/User:SKas" title="User:SKas">SKas</a> (CC BY-SA 4.0)
Mineral NameDendritic Agate
Chemical FormulaSiO2 (host); MnO2, Fe2O3 (dendrites)
Mohs Hardness7
Crystal Systemtrigonal
Streak ColorWhite (host), Black/Brown (dendrites)
CleavageNone
FractureConchoidal
Specific Gravity2.65
Colorswhite, cream, light green, reddish-brown, dark green, black
TransparencyTranslucent to opaque
Type LocalityRussia
Mineral GroupSilicates (host), Oxides (dendrites)
Usesjewelry, ornamental, collector's specimens
Associated Mineralsquartz, manganese oxides, iron oxides
Rarityuncommon
Description
This is a polished slab of dendritic agate, showcasing intricate, fern-like or tree-like patterns of dark manganese or iron oxides embedded within translucent to opaque chalcedony, which exhibits bands of white, cream, green, and reddish-brown hues.
Geological Context
Dendritic agate forms in silica-rich solutions within cavities or fractures in volcanic or sedimentary rocks, where microcrystalline quartz (chalcedony) precipitates, and later, solutions rich in manganese or iron oxides infiltrate and crystallize in branching, tree-like patterns.
