Citation: Brigatti, M F; Davoli, P (1990). Crystal structure refinement of 1M plutonic biotites. American Mineralogist, 75, pp. 305-313.
Formula: Al Fe H2 K Mg2 O12 Si3
Chemical name: Potassium iron dimagnesium phyllo-alumotrisilicate dihydroxide
List type: noninterleaving
List: 2D
Basis: (1;0;0 0;1;0)
Dimensionality: 2
Formula: Al8 Fe2 H4 Mg4 O24 Si8 (Al4 Fe H2 Mg2 O12 Si4)
Multiplicity: 1