12th Annual Smithsonian Magazine Photo Contest Natural World
Crystallites of pyrite in clayey limestone

Pyrite crystallites formed by bacterial activity inside cocoon-like structures. The bacteria are iron-eating types feeding on iron removed from clayey minerals in limestone. The limestone is a construction stone and the pyrite (an iron sulphide also referred to as Fool's Gold) forms a patina surface which is most damaging to buildings. The scale (lower right) represent 10 microns. A micron is a thousandth of a millimeter.

Photo Detail
Date Taken: 08.2012
Date Uploaded: 11.2014
Photo Location: Jerusalem, Israel
Copyright: © Aryeh Shimron