Injured was bent over cleaning crosscut for pumpable crib bags to be hung,a piece of coal(approx.3'x1.5'x6"")fell from the mine roof and struck them in the back. It didn't involve any equip. or compliance issues. It also didn't involve job skills, training, PPE or protective devices.**EE returned to work on next scheduled shift,03/26/18, then began missing work on 3/27/18.