Umangite (very rare) (ex Josef Vajdák)

Item Description

An incredibly rare specimen of the copper selenide Umangite from the Tumiñico Mine in Argentina, which is often mistaken for the type locality. Interestingly the co-type locality is the Las Asperezas Mine, but the species is named after the Umango Mountains. This is direct from mindat.org, "The 'Sierra de Umango' is famous for its selenide-rich hydrothermal vein systems, and gave its name to the selenide species umangite. However, there are no selenides at all in the Sierra de Umango sensu stricto - the selenium mines are all in the Sierra de Cacho, a parallel mountain range just to the west of the Sierra de Umango, and separated from it by a long valley including the two Barreal salt flats. The source of this error seems to have been the mine engineer Emilio Hünicken, ex-student at the Clausthal Mining Academy, who provided the first specimens of "Sierra de Umango" eucairite, tiemannite and what would become umangite to Klockmann around 1890. (Klockmann, F. (1891) XVIII Mineralogische Mitteilungen aus den Sammlungen der Bergakademie zu Clausthal. 1. Über einige seltene argentinische Mineralien. Zeitschrift für Kristallographie, 19, 265-275.)" This specimen hosts bluish-black Umangite with minor blue Chaclomenite on host rock matrix. This is one of only a handful of pieces of this species that we've seen, and comes with a classic label from Josef Vajdák / Pequa Rare Minerals, which immediately increases the value (though he mistakenly has the Tumiñico Mine listed as the type locality for Umangite). You can read Joe's biography here: http://www.minrec.org/labels.asp?colid=1371. Additionally, there is a photocopied label from Dr. Werner Paar attached to Vajdák's label.