Cylindrite (rare) (ex Kay Robertson Collection)

Item Description

Cylindrite is a rare sulfosalt that forms in uniquely tubular / cylindrical shaped crystals. This specimen is from the type locality for the species, the Santa Cruz Mine in Poopo, Bolivia. The best examples of the species are found at this mine, and pieces are still being found today. This small cabinet specimen features dozens if not hundreds of thin, prismatic, silvery-grey colored cylinder shaped crystals of Cylindrite measuring up to 1.5 cm long which are tightly intergrown to create a showy overall specimen. Interestingly, there are a few species in the Cylindrite group, and it is the only group of minerals that forms in naturally "round" crystals. Additionally, when attempts to grow synthetic Cylindrite have been made, the crystals actually grow with rigid angles and not their typical cylindrical form seen in nature. Ex Kay Robertson Collection (#12963). The labels accompanying the piece state that it is associated with Incaite, which is no longer a valid species and now defined as a variety of Franckeite. Kay is a prominent California collector, who specialized in European classics (see the article in the March-April, 2007 Mineralogical Record and the 50+ page article in the German Magazine "Mineralien Welt" November-December 2017).