Marble is a calcium-rich stone, porous and susceptible to expansion. When spills are left on a marble countertop, they seep into the pores. Over time, this leads to cracks. It’s important to wipe up any spills immediately, then wipe the area with a little water and dry immediately. Never allow wet dishes, glasses or water to stand on a marble countertop for any length of time. Water will seep into the stone and leave a permanent ring to remind you where the water was. This is caused by a permanent change in the marble’s composition and can only be removed by professional polishing. Cleaning Agents Matter
You’ll need to select a cleaning solution that is made specifically for cleaning marble. Most regular household cleaners contain acid, which can damage the finish. Cleaners with citric acid must be avoided. Neutral cleaners, such as phosphate-free solutions or dishwashing liquids, will work in a pinch. The trick to using any cleaning agent on your countertop is to rinse the soap off immediately with warm water to avoid drying out the marble.
If your marble countertop is stained, you may need to choose between living with the stain and living with an etched surface, as most cleaners that can do the job will also do some damage to the finish. For stains from oils in foods, spread dry corn starch over the stain and let it sit for 24 hours. This should absorb most of the oil from the stain.