Siderite / Hematite (iridescent) (ex Kay Robertson Collection)

Item Description

This is a classic specimen of the elusive Siderites from the Farmsen Clay Pit in Hildesheim. Highly compressed, beautiful chocolate brown colored rhombohedra of Siderite measuring up to 1.2 cm across sit atop a prior generation iridescent semi-spherical Siderite which formed over septarian nodule matrix. The label states that the Siderite is sitting on Hematite, but I think the Hematite is coating everything to create the iridescent effect. One reference I found online stated that these specimens were collected in 1958. Ex Kay Robertson Collection (#784). 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 Velt" November-December 2017).