WHILE WAITING ON THE OPERATOR SIDE ROOF BOLTER TO FINISH SETTING A BOLT, EE LAID HIS LEFT HAND ON THE TOOL TRAY. A ROCK MEASURING 9""L,4""W,3""THICK FELL FROM BETWEEN THE BOLTS STRIKING HIS LEFT HAND LACERATING THE POSTERIOR METACARPAL FOR A DISTANCE OF APPROX 3"". THIS REQUIRED 30 SUTURES TO CLOSE THE WOUND. NO DAYS WERE LOST. THIS IS TO REPORT MEDICAL TREATMENT ONLY. THIS OCCURRED ON