Equivalent reagents include sodium aluminate and sodium silicate. Common pigments used in phosphorescent materials include zinc sulfide and strontium aluminate. Strontium aluminate cement can be used as refractory structural material. Calcium aluminate cements are cements consisting predominantly of hydraulic calcium aluminates. Tricalcium aluminate and calcium aluminoferrite are other common components. The alumina is converted in sodium aluminate. Calcium aluminate cements are hydraulic cements made primarily from limestone and bauxite. The hydroxyaluminate or hydrated aluminate can be precipitated and then calcined to produce anhydrous aluminates. When the hydroxide concentration becomes sufficiently high the soluble aluminate, , is formed. In the same way, the aluminate, carbonate, or hydroxide may be reduced by magnesium. The use of strontium aluminate cements is limited by the availability of the raw materials. Sodium aluminate solutions are intermediates in the production of zeolites. The hydration reactions of calcium aluminate cements are very complex. The materials in cement clinker are alite, belite, tri-calcium aluminate, and tetra-calcium alumino ferrite. Other components present in cement such as tri-calcium aluminate also interact with sulfate ions.