White, for sure!

Brick or marble?

Dekton or porcelain will be a lot less heavy and less cost.

Is the terrazzo salvageable?

The fireplace facade with the Eames chair is so perfectly MCM. The veined stone is more modern than MCM....MCM was lots of wood, terrazzo, Formica colors like orange or gold in the kitchen...simple and clean.

The brown leather Eames chair ^^^^

Definitely a white porcelain tile of some sort! Also, id suggest having whatever finish you choose go all the way up to the ceiling. It will make that side of the room feel more connected.

Also, keep in mind that with whatever finish you decide to use, make sure your floor/wall is able to accommodate for the additional weight.

Yes felizlady, the terrazzo is fully recoverable!

It will look glossy white and clean, almost new! can’t wait to see it.

Will post before & after pictures here at Houzz.

I know marble is after-MCM period, and I am very period appropriate reno person.

But, I want to balance the decision thinking which way is better ? : to go back to white bricks? or boost the house value a bit with marble ? which still is minimalistic and doesn’t distort too much MCM style (check last picture with white Eames chair).

Revalue of the property might be affected either or.

Thanks to all for such great ideas !

No for brick.