ExCal 400 Calcium carbonate Excalibar Minerals Extenders / Fillers >> Calcium Carbonate, ground ADHESIVE SEALANT Southwest calcium carbonate stone used in energy exploration, plastics and rubber where color is not of principle concern. ExCAL Calcium Carbonate products are processed from a high purity stone, to exacting specifications at our Houston, Texas plant. The grades shown are suitable for use in plastics, adhesives, sealant and other applications. Calcium carbonate. Possesses high purity. Used in adhesives, sealants and other applications.