mineral

Polished dendritic agate (likely Montana or similar jasper-agate)

Microcrystalline quartz, SiO₂, with iron/manganese dendrites

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; brown, amber, cream, and black patterned surface; waxy to vitreous luster; cryptocrystalline quartz with no visible cleavage. The rounded, glossy form is tumbled or polished.

Identified September 3, 2026More mineral →

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Physical properties

Hardness 6.5–7 Mohs; brown, amber, cream, and black patterned surface; waxy to vitreous luster; cryptocrystalline quartz with no visible cleavage. The rounded, glossy form is tumbled or polished.

Formation & geological history

Silica-rich groundwater filled cavities and fractures in volcanic rock, depositing chalcedony and agate over time; dark branching areas commonly derive from manganese or iron oxides. Exact geological age and locality cannot be determined from the image.

Uses & applications

Used as a lapidary stone for cabochons, carvings, jewelry, and collectibles; attractive dendritic specimens have modest decorative value.

Geological facts

Dendritic patterns resemble fossils or plant growth but are usually inorganic mineral precipitates. Agate commonly shows translucency, curved banding, and extremely fine quartz texture.

Field identification & locations

Identify by its glassy/waxy polish, hardness, irregular chalcedony patterns, and absence of true fossil structure; common sources include Brazil, Uruguay, Mexico, India, and Montana. A scratch test and locality information would improve identification.