Lifting a skirt board with a come-a-long when a piece of rock measuring 3' x 2' x 2"" fell from the top and struck him on the left ankle, resulting in a fracture to the ankle. (The employee had returned to work on 7-10-07 with 21 days away from work, worked 2 days and began missing work again on 7/12/07 due to the injury)