Structure of a new upper-mantle, magnetoplumbite-type phase, Ba(Ti3Cr4Fe4Mg)O19.
Article
Grey, IE, Madsen, IC, Haggerty, SE. (1987). Structure of a new upper-mantle, magnetoplumbite-type phase, Ba(Ti3Cr4Fe4Mg)O19.
. AMERICAN MINERALOGIST, 72(5-6), 633-636.
Grey, IE, Madsen, IC, Haggerty, SE. (1987). Structure of a new upper-mantle, magnetoplumbite-type phase, Ba(Ti3Cr4Fe4Mg)O19.
. AMERICAN MINERALOGIST, 72(5-6), 633-636.
The new phase, ideally Ba(Ti3Cr4Fe4Mg)O19, is found in metasomatized lithosphere-derived harzburgite, in the Kimberley district of South Africa. It has hexagonal symmetry, space group P63/mmc, with a 5.871(2), c 23.06(2) A. The crystal structure has been refined to R = 0.044 for 368 independent reflections collected on a diffractometer using MoKalpha radiation. The new mineral has magnetoplumbite-type structure, with a statistical disorder of the cations occupying the bipyramidal site, in positions displaced by 0.2 A on either side of the mirror plane.-J.A.Z.
