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International audience; The Evje-Iveland pegmatite field in Norway contains pegmatites that are known for their rare scandium mineralization. The petrogenesis of these pegmatites has been debated in the literature for nearly a century. Hypotheses for the origin of the pegmatite-forming melt have included either anatexis of the host amphibolite in vapor-absent conditions, wherein scandium is scavenged from the host amphibolite; or magmatic differentiation, wherein scandium is concentrated through magmatic processes. In order to test the hypothesis that the pegmatite-forming melt was sourced from the host amphibolite, partial melting experiments on the host amphibolite have been performed. These experiments were performed at temperatures ranging from 700 to 1064 °C and pressures between 400 and 550 MPa in a piston-cylinder apparatus. The solidus of the host amphibolite has been determined to be approximately 900 °C at 500 MPa and is significantly higher than the temperature of pegmatite formation. Partial melting of

The use of indium in modern technologies has grown in recent decades, creating a growth in indium demand; thus, there is a need to constrain the spatial and temporal distribution of indium-bearing, granite-related deposits. Toward this end, a conceptual model and exploration vectors for the formation of granite-related indium deposits have been developed. The magmatic-hydrothermal system is modeled by consideration of crystal-melt and vapor-melt equilibria. The model calculates the efficiency of removal of indium from a melt into a volatile phase, which may serve as a component of an ore-forming fluid. The results of the model suggest that as the proportion of ferromagnesian minerals increases in the associated granites, the probability of indium ore formation decreases. Further, for a given modal proportion of ferromagnesian minerals, as the modal proportion of amphibole increases, the probability of indium ore formation decreases. Lastly, for a given modal proportion of biotite, as the magnesium content of the biotite increases (as would result from increasing oxidation of the magmatic system), the probability of indium ore formation decreases. Granites with the highest probability of being associated with indium ore formation will typically be part of A- or S-type igneous systems and will likely be highly fractionated (e.g., A-type topaz granites). I-type granites will generally have a lower potential of being associated with indium-bearing deposits. However, some I-type granites may be associated with indium-bearing deposits if the deposits contain granites (sensu stricto) or other related rocks (e.g., alaskites) that lack amphibole or other ferromagnesian phases.

Urbanization contributes to the formation of novel elemental combinations and signatures in terrestrial and aquatic watersheds, also known as ‘chemical cocktails.’ The composition of chemical cocktails evolves across space and time due to: (1) elevated concentrations from anthropogenic sources, (2) accelerated weathering and corrosion of the built environment, (3) increased drainage density and intensification of urban water conveyance systems, and (4) enhanced rates of geochemical transformations due to changes in temperature, ionic strength, pH, and redox potentials. Characterizing chemical cocktails and underlying geochemical processes is necessary for: (1) tracking pollution sources using complex chemical mixtures instead of individual elements or compounds; (2) developing new strategies for co-managing groups of contaminants; (3) identifying proxies for predicting transport of chemical mixtures using continuous sensor data; and (4) determining whether interactive effects of chemical cocktails produce ecosystem-scale impacts greater than the sum of individual chemical stressors. First, we discuss some unique urban geochemical processes which form chemical cocktails, such as urban soil formation, human-accelerated weathering, urban acidification-alkalinization, and freshwater salinization syndrome. Second, we review and synthesize global patterns in concentrations of major ions, carbon and nutrients, and trace elements in urban streams across different world regions and make comparisons with reference conditions. In addition to our global analysis, we highlight examples from some watersheds in the Baltimore-Washington DC region, which show increased transport of major ions, trace metals, and nutrients across streams draining a well-defined land-use gradient. Urbanization increased the concentrations of multiple major and trace elements in streams draining human-dominated watersheds compared to reference conditions. Chemical cocktails of major and trace elements were formed over diurnal cycles coinciding with changes in streamflow, dissolved oxygen, pH, and other variables measured by high-frequency sensors. Some chemical cocktails of major and trace elements were also significantly related to specific conductance (p

Indium demand has increased with the development of new 21st century technologies. The association of indium deposits with felsic igneous rocks suggests a need for increased research on the behavior of indium in magmatic-hydrothermal systems. In order to better understand the relationship between igneous processes and the formation of indium-bearing deposits, experiments have been conducted at 750 and 800 °C and 100 MPa to constrain the partitioning of indium between ferromagnesian (biotite and amphibole) minerals and felsic melts. The partition coefficient D In Bt / Melt ranges from 0.6 ± 0.1 (1 σm (standard deviation of the mean)) to 16 ± 3 (1 σm). The variation in D In Bt / Melt is a function of X Annite Bt (the proportion of Fe2+ in the octahedral site), tetrahedral aluminum, and titanium, such that D In Bt / Melt decreases with increasing X Annite Bt , tetrahedral aluminum, and titanium. D In Amp / Melt has a mean of 36 ± 4 (1 σm) and composition has only a minor effect on the magnitude of D In Amp / Melt . Additionally, an aqueous volatile phase was recovered from select experiments, which provides an initial constraint on D In Vapor / Melt . D In Vapor / Melt can be influenced by the chlorine content of both the vapor and melt, and is estimated to be ~17 ± 5 (1 σm). Theoretical considerations suggest that D In Bt / Melt can be affected above and beyond the effect of X Annite Bt by water fugacity and the activity of the sanidine component in the system. Theoretical considerations suggest that D In Amp / Melt can be affected by the activities of diopside, anorthite, and enstatite in the system and the fugacity of water. These results suggest that the amount of magmatically-derived indium available for ore formation is a function of the proportion of ferromagnesian minerals in the crystallization products of the magma.