Thought you might like something like this

Personally I would not put a mirror there,

IMO the mirror you have reflects nothing worth seeing twice and I don’t think the new one will be any different go get a nice piece of art instead and save a mirror for spot that reflects something instead of the ceiling

Considering the dark surrounding colors..(floor ...fireplace stone and tv screen) ...whatever you select should have a frame that is bold ..interesting ... in a dark color...proportions are hard to see without a picture from further back showing the whole wall

I think the size you want is fine ... you could tape it off, though, to see what you think. I like your idea of a black or brass framed mirror — would look elegant with your fireplace materials.

What would the mirror be reflecting? It looks like it is just reflecting another room? You’ll want to consider that when adding a big mirror, the reflection should be pretty. (Example being across from a window with a beautiful view). If the reflection is another plain wall, then you may want to place a large piece of art over the fireplace instead.

Not sure of the sizes on these mirrors, but I thought you should see the effect each one has on the space.

Art.Generally, I prefer it no wider than the firebox opening,

Love Beverly’s second one ... that kind of antiqued glass is beautiful. And those sizes she’s showing really make a statement.

Mirrors don’t just have to reflect something gorgeous on the other side of the room ... they’re art in their own right and are wonderful at reflecting light, adding dimension, and making a room feel bigger. Classic design.

This thread made me think of this link I’ve had saved a while:

https://curatedinterior.com/parisian-fireplaces-mantel-decor/