Chalcedony

Rumipata, Ichuña District, General Sánchez Cerro Province, Moquegua, Peru

8 x 12 x 14 cm (3⅛ x 4¾ x 5½ inches). 482 grams (1.06 lb).

This refined chalcedony crystal specimen comes from a one-time discovery made in Rumipata, Ichuña District, Moquegua, Peru, within the last decade. Fewer than 100 examples were recovered, among them, only a handful were preserved with this level of completeness, composition, and color balance.

The piece is composed of numerous elongated, prismatic crystal forms that radiate upward and outward in a densely intergrown yet open arrangement. The color is a consistent, pale blue, distributed evenly across all surfaces. The growth is architectural—well-balanced, with an almost sculptural presence—yet entirely natural in its formation.

The specimen began as elongated, prismatic anhydrite crystals that later pseudo-morphed into chalcedony, giving the crystals their atypical shape. This transformation occurred during late-stage hydrothermal silica deposition within Miocene-aged andesitic volcanic rock, dating approximately 12 to 15 million years ago.

Notable for both its intact condition and cohesive form, this piece stands as one of the most refined and complete examples from the discovery. A rare occurrence in the broader chalcedony suite and a fine crystal specimen by any measure.

https://www.sothebys.com/en/buy/auction/2025/natural-history-2/chalcedony