The scarred walls of a mining tunnel at the Mosaic Co. potash mine in Colonsay, Saskatchewan, Canada, on Tuesday, March 22, 2011. Photographer: Daniel Acker
Circular markings appear on the wall where a mining machine previously drilled at the Mosaic Co. potash mine in Colonsay, Saskatchewan, Canada, on Tuesday, March 22, 2011. Photographer: Daniel Acker
