Calcite (RARE locality specimen!) (ex Kay Robertson Collection)

Item Description

The "Calcite Mine" or Hilton Mine or Palm Wash Deposit operated from 1942 to 1944 for the Polaroid Coporation to produce optic grade Calcite in order to make the Polaroid Optical Ring Sight. According to armed-gaurd.com the Polaroid Optical Ring Sight, was a disk-like optical window, with or without a red filter. The sight was used on merchant vessels and fleet auxiliaries as a finder for 3"/50 guns, mainly in 1944. This fine quality Calcite was used to increase the accuracy of the sights used for bombers during WWII. The Calcite mined at this particular locality was used only for making these sights until a synthetic substitute was created. This was the only locality where optic grade Calcite was mined for strategic use during WWII. Thsi piece is the ONLY crystallized example of Calcite that we've seen from this locality. It features a single, highly compressed, sharp, lustrous, translucent to WATER-CLEAR colorless crystal of Calcite (sometimes referred to as "Iceland Spar") with minor yellowish streaks of iron oxide. If you collect Calcite, California minerals or historically significant specimens, don't miss out on this impossibly hard to find piece from this Ex Kay Robertson Collection (#9403). 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).