SO4 would have isolated (unlinked) tetrahedra that are all oxygen anions that are have some sort of metal bound to them. for example Mg2SiO4, Fe2SiO4 I believe it would be called a nesosilicates or orthosilicate. Solution SO4 would have isolated (unlinked) tetrahedra that are all oxygen anions that are have some sort of metal bound to them. for example Mg2SiO4, Fe2SiO4 I believe it would be called a nesosilicates or orthosilicate..