mineral

Polished dendritic agate or jasper

Microcrystalline quartz (SiO₂), likely chalcedony with manganese-oxide dendrites

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; gray-white body with black branching inclusions, waxy to vitreous luster, cryptocrystalline structure, and no obvious cleavage. The rounded, smooth surface indicates tumbling or polishing.

Identified August 11, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities or fractures, depositing chalcedony; dark manganese or iron oxides create the fern-like dendrites. Agate formation commonly occurred in volcanic cavities during the Cenozoic, though age depends on locality.

Uses & applications

Used for cabochons, beads, carvings, ornamental objects, and inexpensive collector specimens; its hardness makes it durable jewelry material.

Geological facts

Dendritic patterns are mineral inclusions, not fossils or actual plant impressions. The specimen may also be marketed as dendritic jasper, although trade names are inconsistently applied.

Field identification & locations

Identify by testing for quartz-level hardness, examining the waxy cryptocrystalline texture, and noting branching black inclusions; common sources include India, Brazil, Mexico, and Madagascar. Avoid confusing it with dyed stone or glass.