EE scaled a piece of rock from the top in the track entry. When he bent over to remove the rock another piece fell and struck him in the back. EE started missing work on 8/11/10. Could not contact him to find out reason for missing work. Rec. info. from Comp. on 8/20/10 that EE had been off work due to injury. After rec. this info. it is determined to be a lost time accident.