In Dragon Age: Origins where do I find the character to teach me the arcane warrior specialty?

It's unlocked during the Dalish Elf part of the game.In Dragon Age: Origins where do I find the character to teach me the arcane warrior specialty?
During the Dalish elf part of the game you will be sent into a temple full of were-wolves. In that temple (As the place is a maze it will be impossible for me to be exact) on the lower floor there is a room filled with rubble, there you will find a tiny gem, talk to the gem and it will tell you how to be an arcane warrior