Siliceous Sinter ("Kieselsinter") (ex Kay Robertson Collection)

Item Description

Wikipedia defines Sinter as "a mineral deposit that presents a porous or vesicular texture; its structure shows small cavities. These may be siliceous deposits or calcareous deposits". Material like "Geyserite" is a Sinter, and is typically found is amorphous, off-white colored, semi-rounded / radial growths. Chemically I suppose it could be described more like Opal than Quartz because of the water content. With that said, this piece is the only specimen of Sinter that I have seen from Iceland (both labels mention that it was literally found in a "geyser in Iceland". If you collect oddities or rare phenomenon minerals, don't miss out on this one. Ex Kay Robertson Collection (#6513) with an old hand-written label from an unknown collector / dealer. 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).