Installing a mantel on rock fireplace

From where I sit, the depth variations of the rock are going to make installing a floating mantle flush, difficult. You can probably do it but be aware you're going to have gaps between the mantel and the rock surface on the back side. As for the mounted TV, that seems to be an easier option. The stone certainly looks sturdy but if I were you, I'd enlist the help of a pro unless you have all the right tools. A drill and a correct bit to penetrate the stone. A pro might even back-fill the hole with a compound to ensure a good anchor.

Unless you never use the fireplace, are you sure it wouldn't get too hot for the TV components? Heat rises. I'd wait until I had a good fire going for a while and check the temps above it. And the soot you see on the rocks above the fireplace would also coat your TV

I have been thinking of a mantel and have the same rock fireplace. The only solution I have come up with is to use a thing they have in hardware stores to give an exact tracing of the rock surface and then cut the wood to match that. Our fireplace is rock over plywood so you might want to check with a carpenter to find the studs to give a more secure mount for the mantel. I am planning on using a 4 " thick by 8" wide beam for the mantle

For the mantel you could remove the stone along the line of the beam with a chisel and hammer and then break the removed stones to fill in any gaps after the beams installed. To attach the beam, drill a couple holes using a bit big enough to put some rebar or steel rods.... https://www.youtube.com/watch?v=Ip1ylTo4qMU

I used black wrought iron braces and rock penetrating screws. The mantle is a 2 inch thick slab of wood, stained and polyurethaned.

In that case, you could make a template out of cardboard and cut the back to fit snuggly along the nooks and crevices of the rock and transfer that to your mantel. You would need to use a masonry drill and bolts to secure it (don't want that expensive TV to fall off - at the same time maybe attach an I-bolt to secure the TV.

The other option is to put a row of bolts in the rock and then set the mantel on top of them (again making sure you secure it - maybe with U-bolts).

Maybe attach a backer board p stone and then attach mantel to that. Any gaps use a quarter round or trim piece. Tv use concrete lag bolts

To attach brace Not sure how to hide cords unless they can go behind mantel

We also had that rock facing on our fireplace. i took the rock off and found that behind the surface there was support? 2x4 's and pieces of plywood and some places there were bricks. I felt like whoever installed the outside just put something that was laying around,behind it to make it appear flat. This was one of the worst remodeling jobs I ever started. My husband tried to put more support in and installed backer board and, I ran cables down behind the backer board so they wouldn't show later. Then I installed tile. We paid someone $1000. To build a mantle and they put a 1x on the top of the tile and around the sides and routed out the edges. The fireplace is gas and it doesn't seem to heat up the tv we mounted on the wall above. I guess if I had it to do all over I would put out the money to have a professional do it. It would have been cheaper and less arguments to just paint the stone to keep down the dust and spiders down. Now we want a new tv and have to figure out how to hook up a new tv with the hidden cables. Maybe we will just have it installed and use a wall cover for the cables.

Honestly, I would forgo the mantel and just mount the tv over the fireplace. The look would be more aesthetic without a mantel (considering the uneven surface). TV wall mounting brackets come with easy to install instructions. Just my opinion.