EE stated while using slate bar to pry piece of rock from mine roof, a separate piece of rock came out of roof in front of slate bar. That piece of rock fell down bar toward EE's face. EE used left hand to block rock. Rock that struck EE's hand was approx. 3'x2'x3"". EE was wearing metacarpal gloves. EE sought medical attention after his shift & was diagnosed w/bruise.