Dear Krystina:
By your description it sounds like you have a bad case of mineral deposits.
If that's the case, no problem: remove the worst with a razor blade (no, it will not scratch your stone) and then finish the job with a heavy-duty alkaline cleaner rated “for natural stone” with chelates in its formula, like MB-3.
If that won't work, you will need to have a stone restoration contractor to come over and determine the situation and the best course of action.
May I ask you now to please read and e-sign our Statement of Purpose at:
http://www.marblecleaning.org/purpose.htm?
Ciao and good luck,
Mauri
Article ID: 1288
Created On: Mon, Mar 3, 2008 at 3:07 PM
Last Updated On: Mon, Mar 3, 2008 at 12:00 AM
Authored by: Maurizio Bertoli [mail@mbstone.com]
Online URL: https://marblecleaning.org/knowledgebase/article.php?id=1288