Inosilikaatti

Inosilikaatti is a broad class of silicate minerals characterized by their crystal structure. In this structure, silicate tetrahedra (SiO4) are linked together in infinite double chains. Each silicon atom is bonded to four oxygen atoms, and in inosilicates, each silicon atom is also bonded to two other silicon atoms through shared oxygen atoms. This forms a repeating [-Si2O6-] or [-SiO3-] unit along the chain. The resulting structure has a distinctively fibrous or prismatic habit in many of its mineral species.

The double chain structure of inosilicates allows for the incorporation of various metal cations within the crystal lattice, primarily between the chains, which balances the negative charge of the silicate framework. Common cations found in inosilicates include magnesium (Mg), iron (Fe), calcium (Ca), sodium (Na), and aluminum (Al). The specific combination and arrangement of these cations significantly influence the physical and chemical properties of individual inosilicate minerals.

The most prominent group of inosilicates is the pyroxene group, which typically exhibits a monoclinic or orthorhombic crystal system. Examples include enstatite (MgSiO3), ferrosilite (FeSiO3), and diopside (CaMgSi2O6). Another important group is the amphibole group, which shares the double chain silicate structure but typically contains hydroxyl (OH) or fluoride (F) ions within the structure, leading to a monoclinic crystal system and a more complex chemical formula. Common amphiboles include hornblende and tremolite. Inosilicates are widespread in igneous and metamorphic rocks, and their presence and composition provide valuable information about the geological conditions under which they formed.