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The relationships between the mineralogical, chemical and petrological characteristics of cement clinker minerals and the quality of the resultant Portland cement, is of great interest to producers and users of cement and concrete. To examine these relationships, different types of cement clinkers from wet,semi-dry and dry process production kilns were analysed and then tested for quality using British Standard tests. The mineralogical and petrological properties of the calcium silicates, aluminates, ferrites and alkali sulphates were studied. From several thousand mineral analyses performed with an electron microprobe analysis unit, the substitution systems for the different minerals and polymorphs have been determined. The mineral analyses of the various cement clinkers have been plotted on ternary phase diagrams. The different mineral assemblages of the clinkers have been used to assess the effects of composition and production process on the cement clinkers. All the analyses of the characteristics of the minerals and the quality of the cement have been compared using a trend analysis, developed by the author. This analysis establishes which characteristics have a significant effect on the strength of the Portland cement. The role of potassium in the cement clinker and particularly its substitution into the belite phase, is crucial. The reasons for this influence and a relationship between the potassium substitution in the belite and the 28 day compressive strength of the cement is presented.

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Water samples were collected from 20 representative sites in North Derbyshire and N.E. Cheshire at intervals varying from hourly to monthly over a three-year period. All samples were analysed for all major and some minor components. The results were used to evaluate controls on temporal variability, to examine water classification techniques and to identify aquifer types. Additionally, the results from 62 further sites were used with other published results to evaluate geochemical controls on water composition over the whole Derbyshire karst. A complete spectrum of water chemistry types related to hydrological regime was identified by indicators suggested by other workers and new parameters discovered and developed during the present work. The complete spectrum that previous studies have only partly characterized includes highly variable surface streams, intermediate types and saturated diffuse flow resurgences whose variability approaches the precision of the analytical methods. Particularly successful new indicators were the ionic ratios (Ca + Mg)/(Na + K); Ca/(Cl + SO4); Cl/(Na + K) and relative entropy. The final concentration of dissolved calcium was related to the solubility of calcite, calcite precipitation under open system conditions and ion exchange. The dominant control on temporal variability of conduit resurgences was rainfall during the preceding 48 hours. The dominant geochemical3 process was limestone solution and erosion rates of 55 12 m3/km2/yr were deduced, of which 40% occurs at the surface. Other geochemical controls were contact with or the presence of shale, dolomite or lava in the catchment. Further, pollution by road salt or fertilizer and open or closed system evolution were factors. Thermodynamic studies have shown: the dominant ion-pairs are CaSO4, CaHCO3 and MgSO4 in non-thermal waters; the waters are stable with respect only to kaolinite and saturation levels to calcite and dolomite are influenced by the Ca/Mg ratio. Flood pulse and dye tracing studies have shown the Castleton aquifer to be dominantly of a fractured rock type, with some preferential flow paths and many previously unsuspected crosslinks between known caves.

The sector of the Chilean continental margin between 45 and 46 S has been the site of arc volcanism and plutonism since the mid-Jurassic, when magmatism shifted several hundred kilometres westwards from its earlier position in Argentina and became focussed in the fore-arc accretionary wedge of mainly low-grade, continent-derived metasediments. Despite the fact that the metasedimentary basement forms readily fusible crust, Rb-Sr isotopic analysis indicates that it can only have contributed a very minor component to the Jurassic - Tertiary Patagonian batholith. The arc has been subjected to several phases of extension and compression. A restricted back-arc, largely sedimentary, marine basin formed in the Late Jurassic and was destroyed in the mid-Cretaceous without significant deformation of the basin infill, when uplift and voluminous silicic plutonism and volcanism occurred in the back-arc regions. Extension in the western part of the arc gave rise to an intra-arc basin that was the site of submarine mafic volcanism. A major compressive phase in the Miocene caused underthrusting of the crust of the intra-arc basin beneath the main arc to the east, where deep parts of the Patagonian batholith are now exposed in a foliated plutonic complex consisting mainly of gabbros, diorites, quartz diorites and tonalites. At the junction between the intra-arc basin and the plutonic complex are metamorphic complexes formed from the volcanics and sediments of the basin. The alternating phases of extension and compression influenced the compositions of magmas generated and emplaced within the arc. Extensional phases enabled magmas to traverse the crust rapidly in small, compositionally diverse batches (e.g. calc-alkaline, MORB-like and enriched, within-plate magma types). On the other hand, compressive phases hindered the passage of mantle-derived magmas through the crust, favouring their accumulation at depth. There they mixed to produce calc-alkaline mafic magmas of more uniform character and caused anatexis of amphibolitic lower crust and the generation of large volumes of silicic magma which mostly crystallised within the crust.

On the west of Chalkidiki peninsula and on the north of Evia Island, large magnesite deposits occur in dunite and its altered equivalent, brown serpentinite. In the Vavdos district on the west of Chalkidiki peninsula, magnesite veins up to 2m thick and with a lateral and almost uniform extent of more than 100m continue prominently at depths of about 100 m. Most of the substantial magnesite veins in brown serpentinite are surrounded by stockworks of smaller veins. In the Troupi area on Evia Island magnesite occurs as thin veins forming a stock- work-type of mineralisation in brown serpentinite and as the major component of a strong 2 to 3 metres thick, magnesite-serpentine breccia zone. The magnesite is cryptocrystalline, rarely microcrystalline, snow- white in colour, massive or nodular with porcelaneous lustre and conchoidal fracture. It is very pure and the small but variable amounts of Ca and Si and the traces of Fe and Mn shown in microprobe analyses are due to impuritie that occur between cryptocrystalline magnesite grains. The veins are filled with massive magnesite or with magnesite which exhibits smooth, irregular or rounded surfaces (nodular magnesite) with the internodular spaces being saturated with hydrous magnesium silicates. Tremolite, edenite, chlorite, antigorite, and talc are common in the selvages of veins filled with nodular magnesite but they are not genetically related to magnesite mineralisation. Talc is the only one of these minerals that suffered alteration during or shortly after magnesite mineralisation. Talc remnants and its alteration product, lizardite, together with chlorite and minor sepiolite fill the spaces between the magnesite nodules. Pre-existing talc-free, fractures or new structures created by the mineralising fluids were the sites of massive magnesite deposition. Field and laboratory evidence suggest that the deposits were formed from ascending, CO2-bearing fluids, that derived their magnesium content not from the immediately-surrounding country rocks, but from elsewhere and most probably from interaction with ultramafics at depth well below the observable zone of deposition. Experimental work on forsterite interaction with H2O-CO2-0.5 mNaCl solutions together with published data on the solubility of carbonates and silica suggest that ascending CO2-rich fluids that reacted with dunite at depth were able to fill open(ing) fractures with pure magnesite at a later stage in a high pressure-low temperature environment. Strontium isotope analyses indicate that the strontium in the magnesite came largely from carbonate sediments, and this in turn points to connate water or to any ground water isotopically equilibrated with carbonate sediments as the initial source of the mineralising fluids. The spatial relationship betweem the wall rocks of the magnesite and their plate tectonic environment suggest that it is likely that the deposits were formed during the final stages of the emplacement of the ultramafics in their present setting (Late Cretaceous-Eocene?).

Detailed geochemical studies of the dispersion of selected elements (Cu, Pb, Zn, Fe, Mn, As and especially Sn) were undertaken in the drainage sediments of an area on the south-eastern flank of Dartmoor, Devon. The study area is one of mixed geology consisting mainly of the Hercynian granites of the Dartmoor mass, the metamorphosed sedimentary rocks of the adjoining "Killas" and some unmetamor-phosed sedimentary rocks of Carboniferous and Devonian ages. Tin mineralization occurs mainly within the granite area, although minor deposits have been found within the killas. Copper-zinc-arsenic mineralization is limited to the metamorphic and sedimentary sequences. Extensive mining of both types of deposits has been carried out in the past, and contamination is relatively widespread. The sediments of all the streams of the area were systematically sampled at an interval of approximately 1 kilometer. At each site two samples were collected - one panned and one unpanned. Each sample was sieved into a number of size fractions which were then divided into heavy and light components using bromoform. The material was then analysed for the elements listed above by atomic absorption spectro-photometry. Mineralogical investigations were employed in order to study the relationship between the geochemical patterns obtained and the mineralogical composition of the various sets of samples. The data obtained were treated by univariate and multivariate statistical-mathematical techniques, which proved to be of great value in making a reliable interpretation of the results obtained. Frequency distribution analysis, moving averages, correlation coefficients and semi-variograms were all employed. It was found that analysis of heavy concentrates can be used very effectively in exploration for tin and lead deposits. However the analysis of light minerals in the search for tin was found to be equally effective. Analysis of monometallic minerals (tourmaline) might also be used as an exploration tool particularly in the search for new stanniferous regions.