cyclosilicate

The basic structural unit of all silicate minerals is the silicon tetrahedron in which one silicon atom is surrounded by and bonded to (i.e., coordinated with) four oxygen atoms, each at the corner of a regular tetrahedron.

cyclosilicate, compound with a structure in which silicate tetrahedrons (each of which consists of a central silicon atom surrounded by four oxygen atoms at the corners of the tetrahedron) are arranged in rings. Each tetrahedron shares two of its oxygen atoms with other tetrahedrons; the rings formed may have three (e.g., benitoite), four (e.g., axinite), or six members (e.g., beryl). The cyclosilicates have chemical formulas that contain multiples of SiO₃.