Fylosilikáty

Fylosilikáty, also known as sheet silicates, are a major group of minerals belonging to the silicate mineral class. Their defining characteristic is the arrangement of their silicate tetrahedra, [SiO4]4-, which link together to form two-dimensional sheets. In these sheets, each silicon atom is bonded to four oxygen atoms, and each oxygen atom is shared by two silicon atoms. This arrangement results in a planar structure with the formula [Si2O5]2-.

These sheets are then stacked and held together by various cations, such as aluminum, magnesium, iron, and alkali metals, typically bonded to oxygen atoms on either side of the silicate sheets. The type of cation and its arrangement influences the specific properties and classification of fylosilikáty. Common examples include mica minerals like muscovite and biotite, as well as clay minerals such as kaolinite and smectite.

Fylosilikáty are abundant in the Earth's crust and are key components of many rocks, particularly sedimentary and metamorphic rocks. Their layered structure often imparts properties such as perfect cleavage, allowing them to be easily split into thin sheets. This characteristic makes some fylosilikáty, like mica, useful in various industrial applications, including insulation, paints, and cosmetics. Clay minerals, another significant subgroup, are vital in soil formation, ceramics, and as filtering agents. The study of fylosilikáty is important for understanding geological processes, material science, and environmental applications.