Samples of ‘blue clay’ were distributed among nine laboratories in various countries to assess the possibility of quantitative mineralogical determination. The disordered form kaolinite commonly found in fireclays and illite, or mica, were found by all laboratories, as was a material variously described as montmorillonite, swelling material (vermiculite, beidellite or open illite), or intermediate or swelling illite. The next most abundant mineral was quartz. Opal, chlorite, felspar, anatase, and organic matter, all in small quantities, were not all found by any laboratory and traces of calcite and dolomite were observed in one only. The most effective procedure is discussed, and it is concluded that the results are of a semi-quantitative rather than a quantitative nature.

The current position with respect to low temperature synthesis of minerals is reviewed, and attention is directed particularly to the mechanism of synthesis. Possible compositions of the hydrated aluminium ion are considered and the significance of the fact that aluminate ions are necessary to introduce tetrahedral aluminium is discussed. It is concluded that present evidence is insufficient to define the processes exactly.

An extension of earlier work on synthesis is described in which silica and alumina are provided in the form of gels instead of as solutions of salts. The systems with nickel and magnesium at different concentrations have been investigated in the presence and absence of sodium chloride and the products obtained are described.

A description and details of performance are given for a differential thermal apparatus which has been developed at the C.S.I.R.O. Division of Coal Research for use in studies of the mineral matter in coal. An important feature of the design is the block assembly unit, which fits into a vertical furnace, and comprises a stainless steel block in which are the three sample wells and three insulated chromel-alumel thermocouples. The output from the differential thermocouples is applied to a simple transistorized D.C. amplifier before being passed to a recorder which traces simultaneously against time the temperature difference and the temperature. Features of the apparatus which have proved especially attractive in research on coal are its automatic operation, ease of maintenance, and base-line stability. Reproducibility of results is good.

The fine structure of the X-ray absorption spectrum observed on the high energy side of the iron K edge has been recorded with a modified commercial single-crystal X-ray spectrometer. Metallic iron samples exhibited no detectable fine structure, whereas Fe3+ in ferric oxide and Fe2+ in ferrous ammonium sulphate and ferrous sulphate produced significant fine-structure peaks due, presumably, to 1s→4p and 1s→5p electron transitions. The apex of the 1s→4p peak and the minimum between the two peaks were shifted to lower energies by the Fe2+ samples, and the corresponding apices and minima on fine-structure spectra of samples containing Fe3+ and Fe2+ were shifted by an amount which was approximately a linear function of composition. These observations have led to the development of an analytical procedure for the determination of ferric (or ferrous) iron in dry, ground or sedimented clay mineral samples. The lower limit of total iron concentration in the clay sample to which the method is applicable is approximately 1 per cent. The procedure appears promising as an indicator of the oxidation-reduction potential of the geological environment with which the clay mineral may have been in equilibrium, and as a tool of more general geochemical utility.

The occurrence of metahalloysite ‘nodules’ in the silica sand pocket deposits near Brassington, Derbyshire, is recorded for the first time. The geological surroundings are briefly described in an attempt to arrive at an explanation of the genesis of the ‘nodules.’ The history of attempts to work the deposits as china clay in the 18th century is included.

The mineralogical composition of the clay, silt and sand fractions from soil profiles representative of four of Ceylon's major soil groups have been determined using X-ray, differential thermal, optical and chemical methods. The results show that the mineral assemblages in these fractions can be correlated with the pedogenesis and the degree of maturity of the profile.

Two clays of the kaolinite type, one from Bihar and the other from Kerala, were each separated into particle-size fractions greater than and smaller than 1·4 µ.e.s.d. X-ray diffraction, differential thermal analysis, cation-exchange capacity and moisture absorption determinations and chemical analysis of the fractions showed that the micaceous mineral was concentrated in the fine fraction of one whereas it was mostly in the coarse fraction of the other. The evidence suggests that the mineral in the former belongs to the illite group and in the latter to the mica group.

This Conference, organized by the Comit6 International pour l'Etude des Argiles (CIPEA) and sponsored by the International Union of Geological Sciences, was attended by some 200 clay mineralogists from 23 countries. The British Clay Minerals Group was well represented, having 17 participants.

The Conference arrangements were very efficierxtly made by Professor I.Th. Rosenqvist and Dr. P. Graff-Petersen, President and Secretary of CIPEA, together with an Organizing Committee appointed by the Swedish Society for Clay Research, who were the official hosts.