Silicates: group of very common and widespread minerals that make up the majority of rocks on the Earth’s surface, of magmatic origin. Their composition always includes Silicon and Oxygen, often combined in very complex forms with other elements (Aluminum, Iron, Manganese, Magnesium, Calcium, etc.). Structurally, they feature a crystal lattice based on a tetrahedron, with a Silicon atom at the center bonded to four Oxygen atoms located at the vertices. The four remaining valences of the Oxygen atoms can be satisfied by adjacent tetrahedra or by variously arranged metallic cations. Based on the arrangement of the tetrahedra, silicates are classified as nesosilicates, sorosilicates, cyclosilicates, inosilicates, phyllosilicates, and tectosilicates.
