Robertsite, Ca(2)Mn(III) (3)O(2)(PO(4))(3)·3H(2)O.

ABSTRACT: Robertsite, ideally Ca(2)Mn(3)O(2)(PO(4))(3)·3H(2)O [calcium manganese(III) tris-(orthophosphate) trihydrate], can be associated with the arseniosiderite structural group characterized by the general formula Ca(2)A(3)O(2)(TO(4))(3)·nH(2)O, with A = Fe, Mn; T = As, P; and n = 2 or 3. In this study, single-crystal X-ray diffraction data were used to determine the robertsite structure from a twinned crystal from the type locality, the Tip Top mine, Custer County, South Dakota, USA, and to refine anisotropic displacement parameters for all atoms. The general structural feature of robertsite resembles that of the other two members of the arseniosiderite group, the structures of which have previously been reported. It is characterized by sheets of [MnO(6)] octa-hedra in the form of nine-membered

SUBMITTER: Andrade MB 

PROVIDER: S-EPMC3470121 | biostudies-literature | 2012 Oct

REPOSITORIES: biostudies-literature