Calcium Carbonate is a carrier that can also be found in bath products and makeup. A carrier does just what it sounds like - it helps carry a product to a surface by thinning or thickening the formula or simply ensuring even distribution of the other ingredients in the formula. Without a carrier, the product would not work with the same consistency across a surface. Calcium Carbonate can also be used as an abrasive, making a formula slightly gritty to help remove tough stains from surfaces. It will not harm most surfaces, but before using any abrasive product on softer surfaces, you should test it on an inconspicuous place.