The hearth is a black marble slab. It is supported by a concealed, cantilevered steel frame.

I agree... architect knows!

Do you mean like a plate that mounts to the wall with rods that go into holes drilled in the edge of the marble? I’m looking to do the same thing as a mantle shelf between a fireplace and TV. Is it possible for you to share more specifics for this? I’m happy to pay for your expertise. Happy to connect by phone or email if possible.