Abstract. Additional information about the relative intensities of reflections that overlap in a powder diffraction pattern can be obtained from a polycrystalline sample in which the crystallites are preferentially oriented. If the data are collected and analyzed appropriately, more single-crystal-like reflection intensities can be extracted, and thereby more complex structures solved. This 'texture method' was implemented initially in reflection mode and its power demonstrated with the solution of the 117-atom structure of the high-silica zeolite UTD-1F. However, the experiment required a minimum of 3 days of synchrotron beamtime per sample. In an attempt to reduce the amount of beamtime needed and to simplify the experiment itself, a transmission mode alternative using an area detector was developed. Details of the sample preparation, data collection and data analysis for both geometries are described. The solution of the structures of the aluminophosphates Mu-9 (R 3 3c, a ¼ 14.0696(1) A, c ¼ 42.3113(4) A) and AlPO-M (Pbca, a ¼ 9.7493(1) A, b ¼ 29.1668(2) A, c ¼ 9.3528(1) A) using reflection and transmission mode data, respectively, are provided as examples of the method.

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SWITZERLANDBy exploiting the preferred orientation of the crystallites in a textured polycrystalline sample, the individual intensities of reflections that overlap in 2θ can be estimated more reliably and more single-crystal-like data obtained for structure solution. The viability of this approach has been demonstrated for data collected in reflection mode, but 3 days of synchrotron beamtime are required per sample. In an attempt to reduce the data collection time, to reduce the size of the sample and to obtain more complete data, experiments in transmission mode using a 2-dimensional detector have been performed. Typically 36 image plate frames, each corresponding to a 5° rotation of the sample, are measured. Each of these frames is subsequently divided into 72 radial wedges (5° sample tilt) using the program Fit2d. Thus the dataset consists of 36x72=2592 powder diffraction patterns, each corresponding to a different sample orientation. To analyze this large amount of data, the program Expol has been reorganized and expanded. In the first step of data analysis, an automatic intensity extraction procedure based on the Pawley algorithm is used to obtain pole figure data (intensity change as a function of sample orientation) for non-overlapping reflections. These data are then used to determine the orientation of the crystallites for the subsequent extraction of a single set of reflection intensities from the full dataset. The structure solution of a number of minerals has, in the past eluded crystallographers by virtue of their occurrence only as microcrystalline masses, which make them unsuitable for study by single crystal methods. In such cases, when the symmetry is high, it has often been possible, to establish the crystal structure from the powder diffraction pattern. There remains, however, a group of microcrystalline minerals of monoclinic and triclinic symmetry, for which crystal structure determination has proven to be intractable. The recent development of methods to fit powder diffraction profiles obtained using synchrotron x-ray sources together with the development of new software to accurately extract intensity data from these patterns has made possible the ab inito determination of the structure of microcrystalline compounds. We report here the crystal structures of two such minerals, kingite and priceite. Kingite, Al3(PO4)2(OH,F)3.9H2O from the Fairview phosphate working near Robertstown, South Australia was first described in 1957. The structure solution showed a layer structure consisting of strips of three-corner-linked AlO6 octahedra which are inter-linked by PO4 tetrahedra. Priceite, Ca4B10O19.7H2O, was described in 1873. We obtained a monoclinic cell a = 12.356(1), b = 6.980(1), c = 11.627(1) Å, and b = 110.677(2)º. The structure solution from direct methods showed chains of Ca polyhedra linked by oxygen bridges, further investigation revealed that the Ca polyhedra are also linked via BO3 and BO4 groups. Disordered solvent occupies about a half of macromolecular crystals and the information ...