Using air impact wrench to tighten bolts on case of 3b tailings pump. Impact wrench slipped out of employee's hand, due to ""never sieze"" on his gloves. Smashed his right hand pinky finger between handle of impact wrench and pump pedestal. Employee reported on 9/8/09 that he sought treatment at clinic. Received diagnosis on 9/9/09 statinig he had fractured the pinky finger.