A nearly pure source of calcium carbonate is necessary to refine sugar. It must contain at least 95% calcium carbonate (CaCO) and have a low magnesium content. In addition, the material must meet certain physical requirements so it does not break down when burned. Although caliche does not generally meet all of the requirements for sugar refining, it is used in areas where another source of calcium carbonate, such as limestone, is not present. While caliche requires beneficiation to meet the requirements, its use can still be significantly cheaper than shipping in limestone.