A natural phase with chemical formula Pb2Fe3+Cl3(OH)4·H2O, monoclinic, space group P21, a = 8.033(5), b = 6.253(3), c = 9.221(6) Å, β = 102.98(8)°, was recently discovered within the Etruscan iron slags of Baratti. That phase, denoted as PFC, falls in the category of "geologically modified anthropogenic substances" and therefore cannot be regarded as a new mineral. Full chemical and physical data are given for PFC. Twinning on (001) is ubiquitous. The structure of PFC was solved and refined up to R = 0.082 for 1119 independent reflections collected with MoKα radiation on a twinned crystal. PFC displays a novel structural type, in which layers of face-sharing [PbX9] polyhedra alternate with layers containing columns of edge-sharing [Fe(OH)6] octahedra and structural voids. PFC belongs to a family of OD structures formed by equivalent layers. The OD character of PFC is fully described.
Pb2Fe3+Cl3(OH)4·H2O, a newly discovered natural phase from Tuscany, Italy: physico-chemical data, crystal structure, and OD character
PASERO, MARCO;PERCHIAZZI, NATALE;MERLINO, STEFANO
1997-01-01
Abstract
A natural phase with chemical formula Pb2Fe3+Cl3(OH)4·H2O, monoclinic, space group P21, a = 8.033(5), b = 6.253(3), c = 9.221(6) Å, β = 102.98(8)°, was recently discovered within the Etruscan iron slags of Baratti. That phase, denoted as PFC, falls in the category of "geologically modified anthropogenic substances" and therefore cannot be regarded as a new mineral. Full chemical and physical data are given for PFC. Twinning on (001) is ubiquitous. The structure of PFC was solved and refined up to R = 0.082 for 1119 independent reflections collected with MoKα radiation on a twinned crystal. PFC displays a novel structural type, in which layers of face-sharing [PbX9] polyhedra alternate with layers containing columns of edge-sharing [Fe(OH)6] octahedra and structural voids. PFC belongs to a family of OD structures formed by equivalent layers. The OD character of PFC is fully described.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
