The best way to address mold stains is to use a product that is specifically designed for removing mold and mildew stains on marble such as this one.
You tube remove stains from marble table.
Then apply plastic wrap over the top.
Stains on marble countertop was left by using plumbers putty oil from plumbers putty left greasy stains.
Mix flour into soapy water to make a paste then slather the paste onto your countertop.
Ink stains as with organic stains you can use a poultice made with 6 percent hydrogen peroxide to remove any ink stains.