Modern Craftsman Master Bathroom
What Houzzers are commenting on:
And as far I can see is the miscoleration probably caused by the "underground". As you can see the shape of the "stains" is continued over a couple tiles. This is usually a typical sign when the marble was installed directly on the wood floor (hopefully plywood) without installing any waterproofing membrane before. The "ingredients" from the plywood dissolve when the wood gets wet/dump and travel upwards through the marble tiles. Marble is very porous and act like a sponge. How porous it is can you test by yourself when you hold a flashlight behind a bright marble tile. You will see the light spot on the other side. It looks like the marble tile is glowing. !!! And this is the reason why you have to use ONLY special setting materials when installing marble no matter where! Furthermore is this setting material always white ! - Regardless whether it's thickbed or if it's thinbed mortar. The scenario which John described would cause more "dotted" spots on each marble tile. This pattern would look different.
Here, marble tiles line the floor of a contemporary bath. Patterson says there are three questions you should ask yourself when selecting marble. You may find that what some consider a "con," such as the natural patina that develops on marble over time, is actually a "pro" for you.