Calcite on Gypsum (?) (ex Kay Robertson Collection)

Item Description

Please note: Kay's label accompanying this piece states that it is Calcite on Gypsum, but Gypsum is not reported from the Valenciana Mine, and it's very possibly Calcite on Calcite, with two distinctly different habits. The front of the specimen features modified white rhombic crystal clusters of Calcite measuring up to 3.1 cm across sitting on thin, bladed, translucent crystals of either an earlier generation of Calcite or possibly Gypsum. Minor roughness around the edges, but no major damage anywhere. A unique and very different style of Calcite that anything I've seen from this locality. Ex Kay Robertson Collection (#365). 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.