Ketjusilikaatteja

Ketjusilikaatteja, known in English as chain silicates, are a subclass of silicate minerals characterized by their crystal structure. In these minerals, silicate tetrahedra, which are SiO4 units with a silicon atom at the center and four oxygen atoms at the corners, are linked together in continuous chains. Each silicon atom shares two of its oxygen atoms with adjacent tetrahedra, forming a one-dimensional chain structure. The general chemical formula for single-chain silicates, also known as inosilicates, is typically of the form XnSiO3n, where X represents cations such as magnesium, iron, calcium, or sodium.

The most prominent examples of chain silicates are the pyroxene and amphibole groups. Pyroxenes have a single chain structure, while amphiboles exhibit a double chain structure, where two single chains are linked together. This difference in chain arrangement leads to distinct physical properties and optical characteristics. For instance, pyroxenes typically have single cleavage planes, whereas amphiboles are characterized by two cleavage planes that intersect at approximately 56 and 124 degrees. Chain silicates are common rock-forming minerals found in a wide variety of igneous and metamorphic rocks, playing a significant role in the Earth's crust and upper mantle. Their presence and composition provide valuable insights into the geological processes that formed them.