2007-01-032022-02-032007-01-032022-02-03http://hdl.handle.net/11124/6028Date scanned: 2002-7-19.Held in the Russell L. and Lyn Wood Mining History Archive, Arthur Lakes Library, Colorado School of Mines.Donor: United States Bureau of Mines.Cavity left after a concretion fell out of mine roof. The concretion that fell out is not the one shown in top photograph. Note slickensided surfaces adjacent to cavity.Rights management statement available at: http://library.mines.edu/digital/rights.htmlScenes, undergroundUnderground miningStillImage