mineral

Polished brecciated agate/jasper

Microcrystalline quartz (SiO₂), chiefly chalcedony with iron-oxide and possibly jasper inclusions

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; brown, black, gray, and rusty-orange bands with a waxy to vitreous luster. It has cryptocrystalline quartz structure, no obvious cleavage, conchoidal fracture, and typically specific gravity near 2.6.

Identified September 3, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities and fractures in volcanic rock, later depositing chalcedony and iron oxides in layers or breccia fragments. The exact geological age is locality-dependent, commonly ranging from Paleozoic to Cenozoic.

Uses & applications

Used for cabochons, beads, carvings, tumbled stones, and decorative objects; attractive patterned pieces have modest jewelry and collecting value.

Geological facts

The visible dark, angular zones suggest brecciation, while the polished surface emphasizes contrasting chalcedony and iron staining. Identification can be confirmed by strong polish, translucency at thin edges, and quartz hardness.

Field identification & locations

Commonly found in volcanic terrains and agate-producing regions such as Brazil, Uruguay, Mexico, India, Madagascar, and the western United States. Avoid confusing it with dyed jasper or resin; a steel file should not scratch genuine material.