tektosilikates

Tektosilicates, also called tectosilicates, are a class of silicate minerals in which the silicate tetrahedra (SiO4) share all four oxygen corners with neighboring tetrahedra to form a continuous three-dimensional framework. This complete corner-sharing distinguishes tektosilicates from other silicate groups that build chains or sheets, leaving a porous or rigid 3D network depending on the composition and arrangement of tetrahedra.

In these minerals silicon is often partly substituted by aluminum within the framework, creating negative charges that must be balanced by extra-framework cations such as sodium, potassium, or calcium. The result is a 3D network whose overall composition can be described as a silicon-aluminum framework with interstitial cations and, in some cases, water.

The tektosilicate family includes quartz and its polymorphs (cristobalite and tridymite); feldspars, which comprise alkali feldspars (for example orthoclase and microcline) and plagioclase series minerals (albite to anorthite); as well as feldspathoids and zeolites, which form similar frameworks under different chemical conditions. All share the essential trait of a fully connected silica-alumina framework.

Geologically, tektosilicates are highly important. They make up a large portion of the Earth’s crust, with quartz being one of the most abundant minerals and feldspars constituting the majority of many igneous and metamorphic rocks. Their frameworks influence physical properties such as hardness, melting behavior, and response to weathering, and they play key roles in various industrial applications.