Cleaning marble could be a tricky affair since it is a porous material and usage of acidic substances can damage it. Baking soda is generally used as a solution to get rid of persistent stains on light coloured marble. This, however, cannot be used on dark coloured marble since dark coloured marble tends to be stain-resistant and usage of baking soda can affect the colour. It is believed that baking soda is safe for marble as long as it is used in the right quantity and with care.