AM_Poldervaartite Formula: Ca1.67 Mn.33 Si O5 H2 Name: Poldervaartite Unit cell: 9.398 9.139 10.535 90.0 90.0 90.0 , V=904.83 Space group: PBCA (61)

Dai Y S , Harlow G E , McGhie A R , American Mineralogist , 78 (1993) p.1082-1087, Poldervaartite, Ca(Ca0.5Mn0.5)(SiO3OH)(OH), a new acid nesosilicate from the, Kalahari manganese field, South Africa: Crystal structure and description