AM_Pharmacosiderite Formula: Fe4 As3 O21 H20 Name: Pharmacosiderite Unit cell: 7.9816 7.9816 7.9816 90.0 90.0 90.0 , V=508.48 Space group: P-43M (215)

Buerger M J , Dollase W A , Garaycochea-Wittke I , Zeitschrift fur Kristallographie , 125 (1967) p.92-108, The structure and composition of the mineral pharmacosiderite, Note: the K atom could not be located, Locality: Cornwall, England