Na2Ca2Si8O2028H2O

Na2Ca2Si8O20·28H2O is a hydrated calcium-sodium silicate with an eight-silicon, twenty-oxygen silicate framework that includes twenty-eight water molecules per formula unit. The composition indicates two sodium ions and two calcium ions balancing the silicate network, with water molecules incorporated as hydration.

The precise crystal structure and mineral classification of this exact composition are not well established in the scientific literature. Hydrated silicates can form a range of architectures, from frameworks to layered sheets, and the exact arrangement for this formula would depend on synthesis conditions such as temperature, pressure, and the hydration state.

Laboratory routes to this material could involve hydrothermal or solvothermal synthesis from sources of sodium, calcium, and silicon oxide, under controlled water activity to achieve the specified hydration level. The material is not known as a naturally occurring mineral with this exact formula in major mineral databases; if it occurs in nature, it would be rare and may be difficult to distinguish from related hydrated silicate or zeolite-like phases.

Dehydration is expected to occur upon heating, potentially changing the structure and its properties. Without extensive experimental data, specific physical properties such as color, hardness, and density cannot be reliably stated. At present, the compound does not have established commercial applications and is primarily of interest for academic studies of hydrated silicates and their structural chemistry.

See also: hydrated silicates, calcium silicates, sodium silicates, zeolites.