Silicatephyllosilicate

Silicatephyllosilicate is a term used to describe phyllosilicate minerals, a major subgroup within the silicate class that is defined by sheet-like silicate structures. In standard mineralogy, the preferred term is phyllosilicate; silicatephyllosilicate emphasizes the silicate-sheet nature of these minerals but is not a separate formal category in most references. The phyllosilicate group comprises minerals built from one or more sheets of linked silica tetrahedra that lie parallel to each other, creating a layered architecture.

Structural features of phyllosilicates derive from two main types of sheet stacking. In 1:1 phyllosilicates, a single tetrahedral sheet is paired with a single octahedral sheet. In 2:1 phyllosilicates, two tetrahedral sheets surround an octahedral sheet, forming a sandwich-like structure. The sheets are held together by interlayer bonds and by interlayer cations (such as potassium, sodium, or calcium) or by hydroxide/water in spaces between the layers. This layered arrangement gives rise to characteristic basal cleavage and a tendency for interlayer water to influence physical properties such as plasticity and swelling in clays.

Common examples span two broad subgroups. 1:1 phyllosilicates include minerals like kaolinite and serpentine, which typically have lower cation exchange capacity. 2:1 phyllosilicates include the mica group (muscovite, biotite) and clays such as illite and smectite, which exhibit more complex interlayer chemistry and, in clays, significant swelling and plasticity due to interlayer water.

Formation and occurrence: phyllosilicates form by alteration or weathering of silicate rocks, hydrothermal processes, or low-grade metamorphism. They are widespread in soils, sedimentary rocks, and metamorphic terrains and play key roles in geologic processes, industrial ceramics, and environmental systems.