Pyrokseenimineraalit

Pyrokseenimineraalit, or pyroxenes, are a group of silicate minerals that are essential components of many igneous and metamorphic rocks. They are characterized by their single-chain silicate structure, meaning their silicon-oxygen tetrahedra are linked together in a continuous chain. This structural feature distinguishes them from other silicate mineral groups like feldspars or micas.

The pyroxene group is divided into two main series based on their chemical composition and crystal structure: the clinopyroxenes and the orthopyroxenes. Clinopyroxenes crystallize in the monoclinic crystal system, while orthopyroxenes crystallize in the orthorhombic system. Common members of the clinopyroxene series include augite and diopside, while enstatite and ferrosilite are prominent orthopyroxenes.

Pyroxenes are typically dark-colored minerals, ranging from black to dark green, although some can be lighter in shade depending on their iron content. They often exhibit a prismatic or equant crystal habit and possess two distinct cleavage directions that intersect at nearly right angles (around 87 and 93 degrees). This characteristic cleavage is a key identifier for pyroxenes in hand samples.

These minerals form under a wide range of temperatures and pressures, making them abundant in various geological environments. They are particularly common in mafic and ultramafic igneous rocks like basalt and gabbro, as well as in many metamorphic rocks. Their presence provides valuable clues about the origin and conditions of rock formation.