Fyllosilikaatit

Fyllosilikaatit, or phyllosilicates, are a group of silicate minerals characterized by their layered atomic structure. This structure consists of tetrahedral sheets of silicon and oxygen atoms, with one oxygen atom in each tetrahedron shared between two silicon atoms. These tetrahedral sheets are typically bonded together by octahedral layers of metal cations, such as aluminum, magnesium, or iron, coordinated with oxygen atoms. The general chemical formula for phyllosilicates can be represented as Xn Ym Zp Oq(OH)r, where X, Y, and Z represent cations, and n, m, p, q, and r are stoichiometric coefficients.

The layered structure gives phyllosilicates a distinct set of physical properties, including perfect basal cleavage, meaning they tend to break along planes parallel to the layers. This results in platy or flaky habits. Many phyllosilicates are also soft and have a low specific gravity. They are common components of many igneous, metamorphic, and sedimentary rocks, particularly clays and shales.

Important examples of phyllosilicates include micas, such as muscovite and biotite, which are known for their transparency and electrical insulating properties. Clay minerals, like kaolinite, illite, and smectite (including montmorillonite), are also phyllosilicates. These minerals are vital in soil formation, ceramics, and as adsorbents. Chlorite is another significant group, often found in metamorphic rocks. The specific properties and uses of a phyllosilicate depend heavily on the type of cations present and the precise arrangement of its structural layers.