HELP! I've just installed a brand new polished marble black and white basketweave floor in my 6 x 6 powder room and with only 2 of us living here, plus a weekly housekeeper, the edges of the small marble tiles are blackened with dirt. I tried steam cleaning with the pointy end of the steamer directly on the tiles (like a power washer) and they didn't look too much better. What can I use to keep them sparkling clean? I had this entire room redone and it's gorgeous (distressed black cabinetry, white farmhouse sink, polished nickel plumbing and black and white toile wallpaper) and it's killing me! I really need help with this floor!