SiO4tetraëderen

The silicon-oxygen tetrahedron, often written as SiO4, is a fundamental structural unit in silicate minerals. It consists of a central silicon atom bonded to four oxygen atoms arranged in a tetrahedral geometry. The silicon atom carries a +4 charge, and each oxygen atom carries a -2 charge, resulting in a net charge of -4 for the isolated tetrahedron. However, in silicate minerals, these tetrahedra do not exist in isolation. Instead, they share oxygen atoms with neighboring tetrahedra, forming various complex structures. This sharing of oxygen atoms, known as polymerization, is a key factor in determining the properties of silicate minerals. The arrangement of these linked tetrahedra gives rise to different silicate structures, such as isolated tetrahedra (nesosilicates), paired tetrahedra (sorosilicates), rings (cyclosilicates), chains (inosilicates), sheets (phyllosilicates), and three-dimensional frameworks (tectosilicates). The presence and arrangement of these SiO4 tetrahedra, along with the type and amount of cations present to balance the charge, are the primary determinants of the mineral's classification and physical characteristics, including hardness, cleavage, and density. Understanding the structure and bonding within SiO4 tetrahedra is crucial for comprehending the vast diversity and importance of silicate minerals, which constitute the majority of the Earth's crust.