With the grain in your floor and then the countertop I think a mosaic marble for a back splash will look a little too much. The general rule is to have no more than one patterned fixed element, that would be your countertop, unless you use the same tile in your back splash I would suggest using a gray subway tile, it will add a bit of relief to the marble and the white.

Agree with above, albeit a pretty tile it is too much for what you are doing. You could do a pattern, but not that specific pattern... maybe a chevron....something more linear, a bit longer vs. shorter pieces.

https://regalfloorcoverings.com/emser-tile-marble-chevron-winter-frost-mosaic.html

Thank you! We ended up going with the grey marble subway tile. We bought samples back of the mosaic backsplash and it ended up looking too busy.