Micro-World Gems & Gemology, Spring 2019, Vol. 55, No. 1

Condor Agate from Argentina

Faint hemispheres of fibrous, white chalcedony.
Core of a “Condor” agate containing faint hemispheres of fibrous, white chalcedony. Photomicrograph by Tyler Smith; field of view 14.52 mm.

“Condor” agates from the Mendoza region of Argentina are sought after by collectors for their vibrant colors and sharp banding. This variety of agate is named after the impressive Andean condor, which calls this mountainous region home. One such stone (see above) was recently examined for photomicrography. It displayed intense orange and yellow bands, likely colored by fine hematitic and limonitic concentrations. The banding ended abruptly at an opaque gray mineral interface that demarcated the transparent core. Contained within this lake were ghostly oolitic concretions, some of which enclosed their own hematite particles. Chalcedony is available in a dizzying selection of varieties and is a constant source of inspiring specimens.

Tyler Smith is a staff gemologist at GIA in New York.