How to frame fireplace?

We are doing reno's and decided to remove the hearth and all the brick from the face of the fireplace and chimney. I now am trying to figure out how to frame out the fireplace so that i can mount some concrete board and put faux stone tile. Do i use wood or steel studs? The top half of chimney is covered in drywall and bottom half is bare concrete block. How would i attach studs to the concrete chimney?

Thanks