Roof bolter operator was bolting in #5 right. He was operating the offside drill and as he swung it out to drill a hole, a rock (11""x10""x3"") fell off his canopy, striking his left shoulder. He complained of numbness but received no abrasions or bruising. He refused ambulance care and drove himself to Raleigh General where tests were negative. The doc gave him 2 days off work.