mineral

Banded agate or jasper fragment

Microcrystalline quartz, SiO₂ (likely iron-stained chalcedony)

AI-generated identification · may be incorrect

Small polished or naturally worn reddish-brown fragment with pale parallel bands; quartz hardness is about 7 Mohs, vitreous to waxy luster, cryptocrystalline structure, and no visible cleavage. The image is insufficient for definitive identification; it could also be a banded shell or other iron-rich stone.

Identified August 12, 2026More mineral →

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Physical properties

Formation & geological history

Agate forms when silica-rich groundwater fills cavities in volcanic rock and deposits successive chalcedony layers, commonly during the Cenozoic or older volcanic episodes. Iron oxides create the red-brown coloration.

Uses & applications

Used for cabochons, beads, ornaments, lapidary pieces, and decorative stone; small common fragments have little commercial value.

Geological facts

Agate banding may be straight, curved, or concentric, reflecting changing chemistry during deposition. A polished surface and translucency are useful clues, but this specimen’s scale and image limit confidence.

Field identification & locations

Common in volcanic terrains worldwide, including Brazil, Uruguay, Mexico, India, and the western United States. Check translucency, hardness, and a conchoidal fracture; avoid destructive tests on a possibly valuable specimen.