i use stone cleaner to clean our marble shower walls--- the shower is large enough that they don't seem to get 'dirty'/ soap scummy, so it's very easy. i use same cleaner for our marble floor, but we don't have a marble shower floor, but would probably use the same stuff if we did--although alot more elbow grease i would imagine!

White marbles can contain ferrous minerals(iron). They are also absorbent . The stone can absorb moisture in a shower stall from the sides ,edges and the underneath. It sounds like the stone is absorbing water from the joints. Silicone will help but the yellow stains is the iron oxidizing. It's rust. Sealers don't help this issue much because moisture will find a way in. This doesn't happen all the time with white marbles but every now and again we see this.

You would want something that is made for or says "safe to use on" marble and stone. John Koessler over on the John Bridge forum (a tiler and also a rep for STT products) recommended STT's cleaners EZCLN and HDCLN for my marble, stone and tile--I'd called him to discuss and order their sealer and we discussed cleaners as well (I'd run out of SCI's Marbalex, which we had been using, and can't find it locally any more--if I had to mail order something anyway, it was worth trying the STT cleaners since I was already ordering from him). My Thassos mosaic in the MB is in the process of being installed, so I haven't used anything on it yet! I can say, that I tried the HDCLN on my discolored grout/glass tile backsplash in my kitchen (just above the vent trim at the back of the range), and it worked very well--faster and easier than using OxyClean. I had called STT directly a couple of months ago while I was doing my HW/research on sealers (hated the stuff we'd used in the guest-bath), and spoke with Steven, the owner of STT. Really nice guy (as is John, BTW), and passionate about their products; their effectiveness and safety, etc. Patient, too! Both men have answered my numerous questions and gave me tons of info about the products, their uses, and any other marble and stone questions I had. I'll let you know how well the cleaner(s) work on the marble when I get to start using the MB!

I just started using Seventh Generation Disinfecting Bathroom Cleaner in our new bathrooms. Both have White thassos marble lining the niches with marble shelves, one bathroom has White Thassos marble border tile, the other has hined travertine floor tile and split-face mosaic border tile. I called Seventh Generation to ask if this product is safe for use on (sealed) marble and/or travertine and was told that it is. I use it on the tub surround tile and on the tubs and sinks. I need to use more elbow grease (on the tub) than I did with my fave, Lysol Basin, Tub, and Tile Cleaner, but the Lysol product etched my trav floor in the guest bathroom, so I don't want to use it in the new bathrooms.