can you get little black marks from natural stone tiles ???

[Newhere2]

any advice what I should try? They look like drip marks from someone using a product that doesn't go well with the stone....

renting so not sure what type of stone, just that it is very very difficult to clean! And IMO should never be in a bathroom without being sealed in some way[hmmm]

Any advice very welcome! thx

[Newhere2]

bumping....