AFTER HEARING UNUSUALY NOISE, EE LEFT BUILDING, WALKED OUT ONTO CATWALK TO OBSERVE AC CRUSHER. AFTER SEEING NOTHING WRONG, TURNED TO WALK BACK TO CONTROL BUILDING AND WAS STRUCK JUST ABOVE RIG HT EYE BY A ROCK, THAT APPARENTLY EJECTED FROM CRUSHER TRAVELING 15' UP TO CATWALK WHERE IT STRUCK EE.