AM_Birnessite_3 Formula: Mn.5 O2.544 Na.364 H2.72 Name: Birnessite Unit cell: 2.9513 2.9547 7.334 78.72 101.79 122.33 , V=52.61 Space group: P-1 (2)

Lanson B , Drits V A , Feng Q , Manceau A , American Mineralogist , 87 (2002) p.1662-1671, Structure of synthetic Na-rich birnessite: Evidence for a triclinic, one-layer unit cell