The following stone care and cleaning procedures were edited from Stone Magazine:

Countertop daily cleaning and maintenance:

• Use a mild dishwashing detergent and lukewarm water with a soft cloth or sponge. Do not use too much soap as this may leave a film and cause streaking.
• Rinse the surface thoroughly after washing with the soap and dry with dry cloth . Do not use scouring powders or cream as this may scratch the stone.
• Do not use products that contain lemon, vinegar, or other acids on any calcareous stone such as marble.

Other cleaning:

• To remove soap scum use a solution of ½ cup ammonia to a gallon of water. Do not use frequently as this may eventually dull stone surfaces.
• In outdoor areas, algae can be removed using a mild bleach and water solution.

WARNING

MIXING BLEACH AND AMMONIA CREATES A TOXIC AND LETHAL GAS!!!

Sealing:

• Areas where food is prepared should have a good sealer applied annually. There are many good sealers available for countertops. If you need a good water repellant sealer look for one that contains a silicon derivative such as siloxane, silane, etc. If you are looking for a water and oil repellent sealer, look for one that contains fluropolymers and make sure that it clearly states that it repels both water and oil. Always test an inconspicuous area before applying to the entire countertop. When applying the sealer always follow the manufacturer's instructions. Most sealers can be applied as followed:

1. Clean countertop with a neutral cleaner
2. Remove any stains with the procedures listed below.
3. Allow the stone to dry for several hours.
4. Pour sealer over the entire surface.
5. Spread the sealer over the countertops with cloth or papertowel.
6. Allow sealer to penetrate for 5-10 mintues, blot off remaining sealer.
7. If sealer is completely absorbed in less than 5 minutes, apply more.
8. After 5-10 minutes, blot off remaining sealer.
9. Buff the stone dry with a clean terry cloth and let surface dry for 12 hours before using.

Stain Removal:
Difficult stains that are not removed by normal cleaning procedures may require a poulticing method.

• One method recommended by Fred Hueston of NTC Enterprises in Stone World magazine is a cup of flour and a tablespoon or two of liquid dish detergent mixed together with water to make a past with the consistency of peanut butter or yogurt. Apply it over the stain , and cover it with Saran Wrap. Let it sit overnight and then remove the plastic and let it dry. Then scrap it away. This method will remove many oil based stains.
  
  
• Another recommendation is to mix the following chemicals for a given stain with one cup of flour or poultice material. Add water until you get a thick, yogurt-like consistency.
  
  
• Cooking oil, vegetable oil etc.: Mix one teaspoon of liquid dish detergent
• Rust: Mix 2-3 tablespoons oxalic acid.
• Coffee, tea, etc: Mix 20% hydrogen peroxide. Add no water.
• Ketchup, mustard, etc.: Mix 3 tablespoons of ammonia.
• In summary, when cleaning your natural stone, mild soap and water is best. Keep chemical products away and use coasters. When in doubt, ask a professional.