Sturmanite / Ettringite (ex Kay Robertson Collection)

Item Description

Sharp, chocolate brown, prismatic, well-formed, trigonal crystals of Sturmanite / Ettringite from the Nchwaning Mines in South Africa. As these two species for a solid solution series, it's very possible that both species are present within the same crystals. Excellent condition all around, no real damage that I can see on the display side. Old classic material with robust crystals! Ex Kay Robertson Collection (#11515). 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).