mineral
Tree agate (dendritic agate)
Microcrystalline quartz (SiO₂) with manganese- or iron-oxide dendrites
AI-generated identification · may be incorrectWhite to pale green, opaque chalcedony with dark branching inclusions; waxy to vitreous luster, hardness about 6.5–7 Mohs, cryptocrystalline structure, no cleavage, and specific gravity around 2.6. The rounded surface indicates a polished or tumbled specimen.
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Physical properties
White to pale green, opaque chalcedony with dark branching inclusions; waxy to vitreous luster, hardness about 6.5–7 Mohs, cryptocrystalline structure, no cleavage, and specific gravity around 2.6. The rounded surface indicates a polished or tumbled specimen.
Formation & geological history
Silica-rich groundwater filled cavities and fractures, while manganese or iron oxides formed branching dendrites during deposition. It is generally associated with relatively young volcanic rocks, commonly Cenozoic in age.
Uses & applications
Used as an inexpensive ornamental stone for cabochons, beads, carvings, and tumbled specimens; it has modest collector value rather than major gemstone value.
Geological facts
Despite its plant-like patterns, dendritic agate contains no fossilized vegetation. The branching markings are mineral-growth patterns, not true crystals or biological structures.
Field identification & locations
Identify it by testing for glassy/waxy chalcedony, lack of cleavage, and natural dark dendrites; it should not show perfectly painted patterns. Common sources include India, Brazil, Uruguay, Mexico, and the United States.
