Pyrosilicic

Pyrosilicic is a term that can refer to several related concepts within chemistry and geology. In a chemical context, it generally pertains to compounds or structures involving silicon and oxygen where multiple silicon atoms are linked together through oxygen bridges. This contrasts with orthosilicates, which contain isolated silicon-oxygen tetrahedra. The term "pyro" often implies a dimer or a condensation product, suggesting the linking of two silicate units.

In silicate mineralogy, pyrosilicates represent a specific structural class. Minerals in this group are characterized by the presence of the [Si2O7]6− anion. This anion is formed by the sharing of a single oxygen atom between two SiO4 tetrahedra, creating a double tetrahedron structure. Examples of pyrosilicate minerals include datolite and hemimorphite. These minerals often exhibit distinct physical properties owing to their specific crystal structures. The arrangement of these pyrosilicate groups, along with interstitial cations, determines the overall mineralogical properties such as hardness, cleavage, and optical characteristics.

The term pyrosilicate might also be used in a broader sense to describe any silicate material formed at high temperatures, although this usage is less common and can be ambiguous. The formation of Si-O-Si bonds is a fundamental process in the creation of many silicate materials, including glasses and ceramics, which are often processed at elevated temperatures. However, when referring to specific chemical structures, the [Si2O7]6− anion is the most precise meaning.