1. Sorosilicates Minerals with isolated [Si2O7]6- groups,
but some have both
[SiO4]4- and [Si2O7]6-
groups.

2. Lawsonite
CaAl2Si2O7(OH)2∙H2O

3. Epidote Group
The group has the general formula X3Y2(SiO4)(Si2O7)(O,OH)
X Y
Ca Al,Fe3+ epidote monocl.
Ca Al clinozoisite monocl.
zoisite orthorh.
La,Ce,Y Al, Fe3+ allanite monocl.
(allanite is an REE-rich epidote; modern naming follows the convention, e.g. allanite-Y)
Ca Al, Fe3+,Mn piemontite monocl.

4. Epidote

5. Epidote, Ca2(Al,Fe)Al2O[SiO4][Si2O7](OH)
monoclinic, P21/m
Tetrrahedral Si, 8-fold Ca (green), chains of Octahedral AlO6 and AlO4(OH)2 , Al,Fe Otahedral (brown)

6. Clinozoisite Ca2Al3Si3O12(OH)

7. Vesuvianite
(Idocrase)
Ca10(Mg,Fe)2Al4(SiO4)5(Si2O7)2(OH)4