Should it be sealed as it will be in the bathroom

Should it be sealed as it will be in the bathroom Images

Should it be sealed as it will be in the bathroom

Should it be sealed as it will be in the bathroom Description

Hello there to the guru of Marble (http://www.lightemprador.com) !
 
I bought an antique sideboard with a white Marble (http://www.lightemprador.com) top for my bathroom vanity. The top has some yellow stains on it, as I have heard you be asked several times on your site. But, you repeatedly said "forgot about them"?
 
How would you recommend I clean this not knowing what kind of Marble (http://www.lightemprador.com) it is? Should it be sealed as it will be in the bathroom?  Any advice would be greatly appreciated.
 
Margaret Miller.