AM_Hellandite-(Y)
Formula: (Al.55 Fe.45) Y2.622 Ca2.616 Si4 B4 H2 O24
Name: Hellandite-(Y)
Unit cell: 18.99 4.715 10.3 90.0 111.4 90.0 , V=858.66
Space group: P12/A1 (13)

Mellini M , Merlino S , American Mineralogist , 62 (1977) p.89-99, Hellandite: a new type of silicoborate chain