EMPLOYEE WAS USING A HAMMER WITH HIS RIGHT HAND TO UNLOG A PIPE BLOWLINE AND FAILED TO SEE WHEREHE HAD HIS LEFT HAND POSITIONED. HE STRUCK HIS LEFT HAND THUMB WITH HAMMER, SUSTAINING A CONTU- SION AND FRACTURE TO VERY TIP OF LEFT THUMB; THEWOUND WAS CLEANED; FINGER GUARD APPLIED; FOLLOW-ING DAY TAKEN TO CLINIC TO HAVE PRESSURE UNDER NAIL RELIEVED; X-RAYS SHOW FRACTURED THUMB TIP.