EE walked up to talk to the C.M. op. when a piece of draw rock fell onto the head of the C.M. and broke into a smaller piece falling down into the conveyor chain. The rock flipped out of the conveyor striking the EE on the Rt. foot & ankle. EE permitted to RTW to reg. duty. EE ret. to Dr. due to pain in his foot 3/7/11 at which time EE was placed on light duty.