That treasure hunter is a great character!
I agree with Ogrob that a dwarf would work well as an Enchanter; that is the school that comes to my mind most readily when I think of dwarves (them being good at making stuff). I could also see a dwarf Wizard as a particularly fierce priest, so maybe a Thaumaturge? Or perhaps a former advisor to a dwarf king, perhaps a Soothsayer?
Having said that, wizards are often considered odd or eccentric even by their own kind, so your magic user does not have to be typical dwarf. He or she might have an undwarvish interest in wildlife and plants outside caves and tunnels (so may be a Witch) or perhaps they have learned how to summon creatures from other planes in a way that unsettles other dwarves, but which is tolerated so long as the gold keeps coming (Summoner). In short, the world is your oyster!
Keep us updated as your band progresses!
