section_path: Classification/Silicates/Sorosilicates
section_name: Sorosilicates
paragraph_text: Sorosilicates
  
  Sorosilicates, also termed disilicates, have tetrahedron-tetrahedron bonding at one oxygen, which results in a 2:7 ratio of silicon to oxygen. The resultant common structural element is the group. The most common disilicates by far are members of the epidote group. Epidotes are found in variety of geologic settings, ranging from mid-ocean ridge to granites to metapelites. Epidotes are built around the structure structure; for example, the mineral species epidote has calcium, aluminium, and ferric iron to charge balance: Ca Al (Fe, Al)(SiO)(Si O)O(OH). The presence of iron as Fe and Fe helps buffer oxygen fugacity, which in turn is a significant factor in petrogenesis.
  
  Other examples of sorosilicates include lawsonite, a metamorphic mineral forming in the blueschist facies (subduction zone setting with low temperature and high pressure), vesuvianite, which takes up a significant amount of calcium in its chemical structure.