dicalcium

Dicalcium is a descriptor used in inorganic chemistry to indicate that two calcium ions are present in a compound’s formula unit. It is not a standalone substance, but rather a naming convention applied to calcium-containing salts, oxides, and silicates to reflect the two Ca2+ ions balancing the chemical structure.

Common examples include dicalcium phosphate, CaHPO4, which exists in hydrated and anhydrous forms. The dicalcium phosphate dihydrate form, CaHPO4·2H2O, is known as brushite, while the anhydrous form is referred to as monetite. These salts are used as dietary supplements and excipients in pharmaceuticals and foods, and dicalcium phosphate is also employed as a mild abrasive in dental products.

Another widely used dicalcium compound is dicalcium silicate, Ca2SiO4, a principal phase in Portland cement. It contributes to early strength development in cementitious materials and interacts with other clinker phases during hydration.

In nomenclature, the term dicalcium signals that two calcium cations are part of the solid’s composition, with the remaining part defined by the accompanying anion or oxide framework. The exact properties of a dicalcium compound—such as solubility, stability, and reactivity—depend on the other elements and the crystal structure present.