Calcium aluminosilicate is an aluminosilicate compound containing calcium cations, most commonly with the chemical formula CaAl<sub>2</sub>Si<sub>2</sub>O<sub>8</sub>. In minerals, as a feldspar, it can be found as anorthite, an end-member of the plagioclase series.
As a food additive, it is sometimes designated E556. The FDA recognizes it as an anti-caking agent for table salt when used at levels below 2% by weight, and as an ingredient in vanilla powder.