I pick up some pretty 12"x12" marble with long vanes for my entry but man
was it ever so fragile. Over 30% breakage or defects: some of it broke as I
just pick it up, some already broke in the box and some with defects. You
could see the factory try to fix the cracked ones by applying some sort of
bond on the back side - but cracked is still cracked regardless of the
attempted repair as you could feel in on the finished surface. Is this your
experience with marble tiles?

I do say it does look very nice and once its set in mud it should be ok.