EMPLOYEE WAS WALKING FROM MINER TO POWER CENTER.A PIECE OF SLATE FELL OUT BETWEEN THE 2ND AND 3RD ROW OF BOLTS STRIKING HIM ON TOP OF HARD HAT AND JAMMED HIS NECK, SLATE WAS 6' LONG 2' WIDE AN D 2' THICK. NO DAMAGE OR IMPAIRMENT TO THE MINING OPERATION OR EQUIPMENT OCCURRED. AWARENESS OF ROOF CONDITIONS MAY HAVE CONTRIBUTED TOT HE ACCIDENT.