This is the stone I love for your fireplace, especially if you are going to use flagstone. Same colour family and with dark wood the wood and stone compliment each other by bringing out their richness and texture.
Really like the idea of a massive fireplace made of stacked stone. The mantle blends in so it disappears. Is this attractive?
I respect Gabriel Builders, the designer of this home. Google him for more wonderful examples of his work.