Determine the architectural units of silicates

This common architectural unit (SiO₄^4- ) of silicates is of remarkable stability. The different silicates may be classified primarily according to the manner in which these SiO₄^4-units become associated with one another. This results into continuous chains, sheets or complete three dimensional structures of silicates depending upon the manner in which the extension of linked tetrahedrons takes place in space. The stability of a given structure is maintained by the complex interplay of geometrical and electrical factors involving all the atoms in the final compound.  The minerals in which one tetrahedral sheet and one octahedral  sheet form the crystal unit, are known as 1:1 type minerals e.g., kaolin, while the crystal unit in which one octahedral sheet is sandwiched between two tetrahedral sheets is called  2:1 type  minerals e.g. montmorillonite. When two tetrahedral sheets are p resent with one shared and one unshared octahedral sheet, a  2:1:1 type  of mineral is obtained e.g. , structures with alternate mica layer followed by brucite layer.