It sounds like an oil stain.
You can use Gel-gloss for cleaning marble. It comes in a pink can at the hardware store.
hello again -
i've got a very old marble sink top (w/ drop-in enameled iron basin) that's stained over a large area.
it's not a surface stain like paint or something superficial - it appears that a substance (perhaps oil or solvent) soaked into the marble over a period of time.
i'm not at all familiar with marble and don't know whether such stains can be altered in any way.
the marble is light colored - beautiful gray / white.
the stain is yellowish.
can anyone comment or suggest who i might ask about this?
I suggest that you go over to www.johnbridge.com and look in their refinisher forum. Note, as of this time I'm writing this, their site seems to be down, but I hope it will be back up soon (doesn't happen often). I don't know anything particular about marble, but they have some stone pros over there that, if anyone can, will be able to help. My guess is that you may need to apply a poultice, possibly more than once. Basically, this is a majic slurry of componenets that you paint onto the stone and let it sit covered up so it stays damp often overnight. It absorbs stains, then you remove it. Depending on what it is, you may not be able to remove it.
Does this go all around the sink? If so, they may have used an oil based caulk or putty under the lip of the sink to seal it to the top, and this has leached into the stone. If you go over there, try to post a picture and describe exactly where it is in more detail. You need to be very careful of what you use on stone, marble especially, or you can get the results you have now. If it is the result of spilling something on there, then that often can't be helped, but you need to ensure you clean it off as quickly and completely as possible.
Important note - I'm not a pro
Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013
wow! what a great duo -
i'll pick up the gel gloss today (sound like a wonder product ... there are a lot of things i can imagine using it for in my house!).
and that website ... amazing ... so much to drink in ... i'll be joining the forum this morning. thanks for steeing me there. looks like i'll be spending quite a bit of time there in days to come ...