Abstract
LONDON Mineralogical Society, June 7.J. E. Drugman and Max H. Hey: Legrandite, a new zinc arsenate. A yellow transparent mineral on a single specimen of blende proved to be a new zinc arsenate. Chemical, optical, goniometric, and X-ray measurements were made, and the name legrandite is proposed for the new mineral, the formula of which is Zn14(AsO4)9OH.12H20. W. F. P. McLintock: The metamorphism produced by the combustion of hydrocarbons in the Tertiary sediments of south-west Persia. At various localities in south-west Persia, the escape and combustion of gas or oil have resulted in the brecciation, partial fusion, and crystallisation of calcareous marls with the formation of crystalline rocks consisting of pyroxene (diopside, girine-augite, and girine), wollastonite, pseudo-wollastonite, bytownite, melilite, and leucite, with glass, recrystallised calcite, and anhydrite. In the field, the rocks resemble vesicular igneous types, but microscopic examination and chemical analyses, accounts of which are given, prove them in all cases to be metamorphosed sediments.F. A. Bannister: The determination of minerals in platinum concentrates from the Transvaal by X-ray methods (with chemical analyses and syntheses by M. H. Hey). X-ray rotation photographs have been used to distinguish and select for chemical analysis the various platinum-and palladium-bearing minerals present in the concentrates of Bushveld platinum ore. The name cooperite is retained for PtS, tetragonal, space-group???. The face-centred unit cell with edges a = 4·91, c = 6·10 A., contains 4PtS. The atomic co-ordinates for platinum in this cell are 1/4 1/4 0; 3/4 3/4 0; 1/4 3/4 1/2; 3/4 1/4 1/2, and for sulphur: 0 0 1/4 0 0 3/4 1/2 1/2 1/4; 1/2 1/2 3/4. The structure is a simple type of fourfold co-ordination built up from plane PtS4 groups and tetrahedral SPt4 groups, the Pt-S distance being 2·32 A. Synthetic PtS has been prepared and is identical with the mineral cooperite. Laurite (RuS2) occurs in small pyritohedral-cubic crystals and has the pyrite structure with unit-cell edge α=5·59 A. The third mineral, PtPdS2, containing about five per cent Ni, is also tetragonal with unit-cell edges a=6·37, c=6·58 A. The unit cell contains 4PtPdS2 and the space group is D???. The name braggite is proposed for this mineral as being the first discovered by X-ray methods.John Parry, Alpheus F. Williams, and F. E. Wright: Bultfonteinite, a new fluorine-bearing hydrous calcium silicate from South Africa. This new mineral was found in the Bultfontein and Dutoitspan diamond mines at Kimberley and in the Jagersfontein mine in Orange River Colony. It forms pale pink globular aggregates of radiating needles, and has much the appearance of natrolite. Analysis gives the formula 2Ca(OH,F)2.SiO2. From the manner in which the mineral is decomposed by water and by dilute acids, a formula written as Ca(OH)2SiO2.Ca(OH,F)2 is suggested. Goniometric and optical examination of the minute crystals shows them to be triclinic, but much complicated by polysynthetic twinning. The mineral is related to afwillite with the addition of Ca(OH)2 and CaF2, and the nearest ally is custerite [CaO.Ca(OH,F)2,SiO2].
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Societies and Academies. Nature 130, 142–144 (1932). https://doi.org/10.1038/130142a0
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DOI: https://doi.org/10.1038/130142a0