"Mine Safety and Health at a Glance" indicates that the increase was driven by a high number of mining deaths in the 4th quarter of 2013 when 15 miners died. In total, there were 42 mining deaths in 2013. Of those 42, 20 occurred at coal mines (unchanged from the previous year) and 22 at metal and nonmetal mines, an increase of six from the previous year. Nine of the metal and nonmetal 22 deaths occurred in the 4th quarter.