Pictures of the whole wall would be useful. But, why do you want any mirror above the fireplace as all you get to look at is a grate on the wall. Hardly interesting.

The round mirror looks pretty good with the geometry of your brick. Would you consider looking for one that is slightly larger with a touch more presence?

Thank you Judy! Would you have any recommendations for decor for the rest of the mantel?

Nobody can give decor advice in a vacuum -- need to see your style, the colors in the room, etc.

@lisaam i think you’re right about maybe putting a mirror with a little more character up! Sometimes I’m a little conservative.

@spiritflower the mirror is leaning on the mantel for right now until I hang it so it’s angled up and the way I took the photo I angled the camera up so you could see the whole fireplace. you won’t actually be looking at the air vent, it will be mirroring the dining room. Thank you for your input 🤗

@acm oh, well I just needed advice on the placement of the mirror since the brick around the fireplace isn’t asymmetrical. I didn’t know if it would look weird to center it on the actual fireplace.

Would definitely center it on the fireplace opening and then use the plant (or something of similar visual weight) to balance the mirror on the right side. Afterward, hang something narrow and horizontal above the plant/whatever is on the mantel. You have something beautiful going.

In the center

It's possible the mirror you have selected is not large enough.

Can we see the rest of the space? I think either could be good, depending on the arrangement of your room (especially seating) and what the mirror reflects in and from the dining room.

I think it looks best centered over the firebox opening. The larger plant you have would help balance out the right side.

I would probably opt for a rectangular mirror or art, but if ypu love the round mirror, center it above the firebox.
BTW, I love your fireplace. So interesting.