I did a search for poultice on the entire site and came up with this. I know a member named stonegirl has given out recipes for poultices that people have used with success, but I can't find it by doing a search. You may want to ask on the kitchen forum where she spends more time. But this looked like what you might need. Here is a link that might be useful: marble link

Cali - I think the tumbled marble is a different story though isn't it? It seems like such a different product to me somehow! bostonpam - I know...it's a risk. But it's the marble countertop that I'd (for me) be most concerned w/ my family destroying. Backsplash gets splattered now and again for sure (especially considering our countertops aren't very deep) but on white marble I imagine I'd see it/notice it often enough to keep it mostly regularly cleaned up. Also, I was wondering if worst-case scenario it couldn't be sanded up or bleach-stained in a certain spot. I'm sure the answer is "ack - no!" but I'd probably go for it if nothing else worked. ;) We'll only be putting in marble (honed or satin I guess) backsplash if we do the countertop in stainless. I think that combo is so darn pretty. Thanks!

Don't discount the fact that the top to your blender might come off while making margaritas. That can get everywhere! (Personal experience.) Or the fact that when you are teaching a youngster how to make a red velvet cake that you forget to tell them one of the first things about using a mixer is that you don't pull it out of the batter with it running. (Also personal experience, and you have no idea how far flung batter can be until you are cleaning it off of the ceiling 15' away from the accident.) Then there's the time my sister didn't really put the espresso maker together correctly and tried to make a pot. Thankfully, that wasn't my kitchen, and no actual bloodshed resulted, but you can bet she'd rather make a run to Starbucks these days than clean up those grounds. And the dent in the underside of the cabinet is still there, but you have to stand on your head to really see it. Then there was the time the cat had an ear abcess and the first I really knew of it (super fuzzy guy) was the blood he had slung all over the kitchen when he shook his head when it burst. Even with him on the floor, yes, it went everywhere and was a bear to clean off of the painted walls. I'd hate to think about a more porous stone with it on it. There was also the mess from the brother in law who cleaned fish in the kitchen.....and the spouse who thought it would be a great idea to use a spray cleaner on a greasy engine part and splattered that black yucky grease everywhere when the cleaner hit it.....and the time that the fruit punch spilled into the cooler, and instead of pouring that outside, a brilliant soul decided to try to pour it down the kitchen sink and splashed it everywhere.......and I could go on and on. I don't think my stories are too atypical of a lot of the wear and tear a kitchen will see over time, and I could never see putting in a surface that wasn't easily cleanable and stain resistant, even if your kitchen's occupants are more thoughtful and well behaved. I couldn't ever be a marble person, anywhere in the home. There's too much life being lived here to have to worry about delicate surfaces.

Update - We finally had the repair done. When the tiles were pulled off, the tile guy found a broken piece of wood about 6" long. I recall that the original installer had used full length boards as temporary overnight supports. We speculated that when he removed the board, part of it broke off and he either wasn't aware or didn't bother to retrieve it. In any event, the wood was quite wet and had obviously been leaching through the tile for some time. Problem solved! Thanks so much for all the input. Nobody got the right answer, unfortunately, but at least we got it figured out.