Birnessite
Post J E, Veblen D R
American Mineralogist 75 (1990) 477-489
Crystal structure determinations of synthetic sodium, magnesium and potassium
birnessite using TEM and the Rietveld method
Sample: K-birn
_database_code_amcsd 0001302
5.149 2.843 7.176 90 100.76 90 C2/m
atom    x y    z  occ Biso
Mn      0 0    0       0.5
O1   .365 0 .136       1.0
K    .723 0 .522 .115  1.5
Wat2 .723 0 .522 .275  1.5
Wat3    0 0   .5  .15  1.5