Note: If you receive a pouch from Baldea called an Orgel then you have the Gold Coin Quest (Wiping out the Ghosts Quest). Drop both the pouch and the Quest from your inventory and your will receive the signature or you can finish the quest first and come back to Baldea later. - Remember always walk to the RIGHT inside the Clements Mine to find Baldea. It is quite complicated so try your best keep walking to the right hand side.