GENERAL GEOLOGY

Detailed explanation-1: -In amphibole structures, the silica tetrahedra are linked in a double chain that has an oxygen-to-silicon ratio lower than that of pyroxene, and hence still fewer cations are necessary to balance the charge. Amphibole is even more permissive than pyroxene and its compositions can be very complex.

Detailed explanation-2: -Silicate minerals are the most common of Earth’s minerals and include quartz, feldspar, mica, amphibole, pyroxene, and olivine. Silica tetrahedra, made up of silicon and oxygen, form chains, sheets, and frameworks, and bond with other cations to form silicate minerals.

Detailed explanation-3: -Cyclosilicates, in contrast, are arranged in rings made up of three, four, or six tetrahedral units. Inosilicates show a single-chain structure wherein each tetrahedron shares two oxygen atoms. Phyllosilicates have a sheet structure in which each tetrahedron shares one oxygen atom with each of three other tetrahedrons.

Detailed explanation-4: -Silica tetrahedra are bonded in three-dimensional frameworks in both the feldspars and quartz. These are non-ferromagnesian minerals-they don’t contain any iron or magnesium. In addition to silica tetrahedra, feldspars include the cations aluminum, potassium, sodium, and calcium in various combinations.