"Hogbomite" on Spinel partially altering to Corundum (ex Kay Robertson Collection)

Item Description

A classic and now very seldom seen specimen from Dewitts Corners featuring a 5 mm crystal of black Spinel (var: Pleonaste) which is dotted by tiny, black, bladed epitaxial crystals of "Hogbomite" (a now discredited magnesium iron aluminum titanium oxide) sitting on Calcite matrix. Interestingly, the Spinels from this locality actually alter to Corundum, which is the case on this specimen as their is a partial alteration (according to the label). This material is unusual, attractive and rare as hens teeth on the market, so don't miss out! Ex Kay Robertson Collection (#10757). 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).