THE EMPLOYEE JUST COMPLETED PRYING DOWN LOOSE TOP/RIB AROUND THE BOLT MACHINE AND HE WAS WAITING ON HIS BUDDY TO FINISH HIS ROW OF BOLTS. WHILE STANDING BY THE ROOF BOLT MACHINE WITH HIS HANDS RESTING ON TOP OF THE MACHINE A ROCK (10 INCHES X 12 INCHES X 3 INCHES THICK) FELL FROM THE TOP AND STRUCK HIS LEFT HAND. X-RAY NEGATIVE, BRUISE AND 1 DAY RESTRICTED DUTY.