Silica Tetrahedron

Chemical Composition: SiO4

This fundamental structural unit consists of a silicon cation (black in photo) surrounded by four oxygen anions (red in photo), giving it four negative charges. It is found in all silicate minerals (ie. amphibole, olivine, pyroxene, quartz, feldspar, etc.). The silica tetrahedra may be arranged in chains (ex: pyroxenes), double chains (ex. amphiboles), sheets (ex: micas), and frameworks (ex: quartz, feldspars), forming the basic structure of the planet.