Natural chalcopyrite-bearing fluid inclusions from the Red Mountain, Arizona, porphyry copper prospect have been used to experimentally document the movement of hydrogen into and out of fluid inclusions in quartz. Chalcopyrite daughter minerals in inclusions do not dissolve during heating studies of "as collected" quartz vein material. However, after the samples were held at an elevated (but unknown) hydrogen pressure in a cold-seal-type pressure vessel at 600°C and 2.5 kbars for seven days, chalcopyrite daughter crystals dissolve easily and completely during subsequent heating in the fluid inclusion stage. The presence of hydrogen in the re-equilibrated inclusions was confirmed by both Raman microprobe and quadrupole mass spectrometric analyses of the inclusions. Repeated heating of re-equilibrated inclusions to measure the dissolution temperature of chalcopyrite (Tm Cpy) results in a considerably higher Tm Cpy during each successive run until, eventually, the chalcopyrite no longer dissolves when heated to the upper limit of the heating stage. This behavior is interpreted to indicate that hydrogen which had diffused into inclusions during re-equilibration experiments diffused out of the inclusions during microthermometric analyses. The dissolution of chalcopyrite following re-equilibration and its failure to dissolve before re-equilibration are consistent with proposed solubility models for chalcopyrite in aqueous solutions. The rapid movement of hydrogen into inclusions is also consistent with experimentally determined diffusion rates for hydrogen through quartz. These results reinforce conclusions reached by earlier workers who suggested that the failure of some fluid inclusion daughter minerals to dissolve during heating is a result of hydrogen loss. These results also support earlier workers who have suggested that unexpectedly low δD values obtained from inclusion fluids were produced by the preferential movement of hydrogen (relative to deuterium) into fluid inclusions. Synchrotron X-ray Fluorescence (SXRF) analysis is a non-destructive analytical technique that provides compositional information for single fluid inclusions. Quantitative analyses of metals in individual synthetic fluid inclusions were carried out in order to gain an understanding of the accuracy, precision and detection limits of this technique, as well as the optimal shapes, sizes and geometries required for reliable fluid inclusion analysis. Aqueous fluid inclusions containing known concentrations of SrCl₂ were synthesized for the development and the standardization of this technique. Strontium chloride was selected because it is highly soluble, its freezing-point depression is well known (allowing us to confirm the inclusion composition through freezing studies) and the energetic Sr X-rays are only mildly attenuated by quartz. SXRF analyses were performed on beam line X26A of the National Synchrotron Light Source (NSLS) at Brookhaven National Laboratory using an 8 x 12 μm "white" X-ray beam. The analytical volume was calculated based on known beam dimensions and fluid inclusion geometry determined using a modified spindle stage. Elemental concentrations were determined by ratioing the Sr counts from an inclusion to the counts obtained from capillaries of known diameter containing similar solutions. Numerous inclusions from five different samples, each with a different Sr concentration, were analyzed. Within a single population the mean is very close to the correct composition, but the precision is poor, with standard deviations from 10-39% of the mean. Errors in determining the inclusion geometry produce the largest uncertainty in inclusion analysis thereby resulting in poor precision. This requires that numerous inclusions within one population be analyzed and averaged to obtain an accurate metal concentration for that population. The Texaco gasification system developed at the Monte Bello pilot plant efficiently burns petroleum-coke thereby producing syn-gas and electricity. This system produces more electricity than conventional burners, yet the only by-products are pharmaceutical grade sulfur and V-rich slag. Vanadium is known to exist in multiple valence states in compounds which possess a wide range of melting points and physical properties. Consequently, it becomes important to carefully regulate oxygen fugacity throughout the system in order to control vanadium valence state. Wanadium phase equilibria is presently poorly understood, in large part because of the multiple oxidation states of vanadium (-1, 0, +2, +3, +4, and +5) and the difficulty of unequivocally identifying the valence state(s) in many compounds. However, V valence in multi-element phases (especially phases containing other elements of variable valence) cannot be resolved by microprobe analysis alone. Petroleum-coke gasification slags collected from within the gasifier under different oxidation conditions were studied by electron microprobe analysis (EMPA), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. Raman spectrometry in conjunction with microprobe analysis was found to resolve the valence of vanadium in the phases of these slags. Gasifier slag samples are, however, much more complicated. Oxidized samples contain: fine grained (Ca, Mg, Fe, V) oxide matrix of variable composition, (Fe, V, Ni) spinel, (Fe, Al, V, Ni, Mg) spinel, V₂O₅ laths, Al-Si glass blebs and Ni sulfides. Reduced samples contain: crystalline Ca-silicate matrix, subhedral to euhedral (V, Fe, Mg, Al) spinel, subhedral VO₂, Fe and Fe-Ni sulfides, Fe-Ni alloys, and complex Ca-oxide matrix. The different spinel assemblages, the characteristic V-oxides and the distinctly different character of the matrices makes the oxidized and reduced slags readily discernible. / Ph. D.