tektosilikáty

Tektosilikáty, also known as framework silicates, represent the largest and most important group of minerals in the Earth's crust. They are characterized by a three-dimensional framework of silicon-oxygen (SiO4) tetrahedra, where each oxygen atom is shared by two silicon atoms. This sharing results in a general formula of T2O5, where T is a cation, typically silicon. However, aluminum often substitutes for silicon within the tetrahedra, leading to a formula closer to T2O5.33 where T can be silicon or aluminum.

The strong, three-dimensional structure of tektosilikáty contributes to their hardness and stability. Common examples of tektosilikáty include quartz (SiO2), feldspars (such as albite, orthoclase, and anorthite), and feldspathoids. Feldspars are particularly abundant, making up over 60% of the Earth's crust. The presence of other cations, such as sodium, potassium, calcium, barium, and strontium, within the framework, often in the interstitial spaces, determines the specific mineral within the tektosilikát group. These cations are crucial for charge balance when aluminum substitutes for silicon.

Tektosilikáty are found in a wide range of geological environments, from igneous and metamorphic rocks to sedimentary deposits. Their durability means they are also common components of soils and sediments. Their economic importance is significant, as many tektosilikáty are used in construction, ceramics, glassmaking, and as sources of aluminum and other elements. The distinct crystal structures and chemical compositions of tektosilikáty allow for their identification and classification based on X-ray diffraction and chemical analysis.