Gaudefroyite (excellent rare crystal) (ex Kay Robertson Collection)

Item Description

Gaudefroyite is a rare calcium manganese borate, and the finest crystals are found in the Kalahari Manganese Field. This piece was originally labeled as coming from the Black Rock locality, but it has been proven that no crystals of Gaudefroyite were ever found there, despite the numerous specimens bearing those labels from years ago. I can't say for certain if this piece is from the N'Chwaning Mines or the Wessels Mine, so we're leaving it simply as KMF. This piece is a very good example of the species as it is a textbook, hexagonal prism featuring very well-formed, smooth, sharp, lustrous, crystal faces. There is a separation mark on the front face where it was connected to another Gaudefroyite crystal, but it is otherwise in good shape. Typically, Gaudefroyite crystals are very small or very thin, so to find a crystal over 1 cm with good thickness is rather hard to find. A great example for any fan of rare minerals, thumbnails or specimens from the Kalahari Manganese Field. Ex Kay Robertson Collection (#11232). Kay was a prominent California collector, who specialized in European classics. She nearly lived 100 years from April 1920 - March 2020. See the article in the March-April, 2007 Mineralogical Record ( https://www.mineralogicalrecord.com/pdfs/Kay%20Robertson%20Collection.pdf ), and the 50+ page article in the German Magazine "Mineralien Welt" November-December 2017.