Pyrosilicate

A pyrosilicate is a type of chemical compound; either an ionic compound that contains the pyrosilicate anionSi
₂O
₇, or an organic compound with the hexavalent≡O₃Si−O−SiO₃≡group. The anion is also called disilicate or diorthosilicate.

Ionic pyrosilicates can be considered salts of the unstable pyrosilicic acid, H
₆Si
₂O
₇. Unlike the acid, the salts can be stable. Indeed, pyrosilicates occur widely in nature as a class of silicate minerals, specifically the sorosilicates - though some sorosilicate minerals, such as gehlenite, replace one of the silicon atoms with tetracoordinated aluminium or boron, giving the isostructural anions AlSiO7−7 and BSiO7−7.

Some notable synthetic pyrosilicates include

• sodium pyrosilicateNa
  ₆Si
  ₂O
  ₇, a possible component of water glass.
• Na
  ₂Fe
  ₂Si
  ₂O
  ₇, a potential cathode material for batteries.
• Na
  ₂Mn
  ₂Si
  ₂O
  ₇, another potential cathode material.