Start the quest by talking to Chan. He will tell you that Don has been hording Turquoise gems which Chan wants to use to make weapons. Go to the northern part of town and talk to Don who will offer you Turquoise in exchange for 10 Mad Bull's Horn and 1 Wolf's Claw. Head east from Don out of town and follow the path continuing east. You will reach a farm area with a lot of Mad Bulls and Wild Boars. Kill Mad Bulls until you have 10 Mad Bull's Horn. Now head south to coordinates (1950,-100) and wait for the Wolf Pack Leader to spawn. The Wolf Pack Leader respawns three minutes after it was last killed. Kill the leader and take the Wolf's Claw and the 10 Mad Bull's Horn back to Don and trade them for his Turquoise. Bring the Turquoise to Chan to receive your reward.