Inosilikater

Inosilikater are a major class of silicate minerals in which the silicate tetrahedra are linked to form chains. They are divided into single-chain inosilicates (pyroxenes) and double-chain inosilicates (amphiboles). In single-chain pyroxenes, each tetrahedron shares two oxygens with adjacent tetrahedra to form infinite one-dimensional chains with the basic unit SiO3; these chains are linked by metal cations such as magnesium, iron, and calcium. Amphiboles consist of paired chains, producing a double chain with units that accommodate a more complex chemistry, including hydroxyl groups in some minerals.

Prominent pyroxenes include enstatite (MgSiO3), diopside (CaMgSi2O6), and augite (Ca(Mg,Fe,Al)(Si,Al)2O6). Notable amphiboles include hornblende, tremolite, actinolite, and glaucophane. Inosilicates are common in igneous and metamorphic rocks and serve as important indicators of formation conditions. They typically have two cleavage directions; pyroxenes show near 90-degree cleavage, while amphiboles have cleavages at about 60 and 120 degrees. They are commonly green, brown, or black, with a hardness around 5–6 on the Mohs scale. Their chemistry supports wide substitution among magnesium, iron, calcium, sodium, and aluminum, enabling a range of solid-solution series.

Because of their well-defined structures and widespread occurrence, inosilicates are key minerals in petrology, used to interpret the history and conditions of igneous and metamorphic rocks.