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Quartz (Var: Chalcedony) : SiO2

Copyright © Amir C. Akhavan
 
 
 
minID: KKC-EM8

Quartz (Var: Chalcedony) : SiO2

Copyright © Amir C. Akhavan  - This image is copyrighted. Unauthorized reproduction prohibited.

A small piece of silicified limestone with secondary fillings of blueish chalcedony in the voids in between. The blueish chalcedony (see second photo shot in incandescent light) shows a rather strong fluorescence of green color in short-wave UV light. Some of the chalcedony shows a botryoidal habit and can also be overgrown by small quartz crystals. In these cases the fluorescence shows a banding that coincides with the agatoid banding seen in the wall-lining chalcedony. The creme-colored parts are completely silicified (no calcite is left in the matrix), resemble porcelain in places and are almost opaque. They show a white and blueish white fluorescence. Pure blue patches are reflections of the UV lamp.
Width of the specimen: 7cm.
UV photo white balanced to 5000K.
Found in April 2010 in the rubble at the road cut shown in the locality photos. Collection Alfredo Petrov.

This Photo was Mindat.org Photo of the Day - 26th Oct 2011

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Photo added: 27th Apr 2010

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