1. *Purchase (or mine) a normal Dragon Gem, Phoenix Gem, Kylin Gem, or Rainbow Gem in exchange for a Silver Needle.
*Purchase (or mine) a normal Fury Gem, Moon Gem or Violet Gem in exchange for a Gold Needle.
2. Head over to the NPC (Old Miner) outside of Phoenix City mines, located just above the NPC which is used to enter the mines. Speak to the Old Miner, and exchange your gem for a silver/gold needle, accordingly.
3. With needle in inventory, search the sub-floors of the mines for a Blue Mouse, and once found, successfully catch him to claim your prize.
4. Head over to Twin City and speak to General Judd, whom is located at the extreme top left of the Twin City map, to claim your prize!