Na2Ca2Si8O20

Na2Ca2Si8O20 is a calcium-sodium silicate compound defined by the empirical formula Na2Ca2Si8O20. In this composition, eight silicon atoms are present in a silicate framework balanced by two Na+ and two Ca2+ cations and twenty oxide oxygens. The exact crystal structure is not widely reported in standard mineral references, and the formula is encountered mainly in discussions of phase relations in Na-Ca-Si-O systems or in synthetic ceramic research.

In terms of occurrence, there is no widely recognized natural mineral with this exact composition. It has been described in experimental studies of silicate systems and in materials science contexts such as glass-ceramics, where similar alkali-calcium silicate compositions are investigated for tuning thermal and mechanical properties. The arrangement of silicon-oxygen tetrahedra and the way alkali and alkaline-earth cations balance the structure can vary with temperature, pressure, and compositional context, leading to different possible structural motifs within the same general composition.

Because detailed crystallographic data for Na2Ca2Si8O20 are limited, specific physical properties such as hardness, refractive index, and crystal system remain poorly documented in public databases. In practice, this formula is often treated as a model composition illustrating silicate polymerization and the role of mixed sodium and calcium cations in stabilizing silicate networks rather than as a widely used or commercially important material.

See also: sodium-calcium silicates, silicate minerals, alkali silicates, and phase relations in Na-Ca-Si-O systems.