THE EE WAS BOLTING ON THE 5TH ROW, PREPARING TO INSTALL HIS SECOND BOLT IN THE 3 LEFT CROSSCUT ON THE GRASSY MAINS SECTION, WHEN A PIECE OF ROCK 18"" X 8"" X 0"" TO 3"" DISLODGED FROM THE ROOF AND STRUCK HIM ON THE RIGHT ARM 2 INCHES ABOVE THE WRIST CAUSING A LACERATION RESULTING IN 10 SUTURES TO CLOSE THE WOUND.