General Research Interests
• Experimental Mineralogy and Mineral Physics
• Applications of Synchrotron Radiation to Geologic Problems
• High-Temperature Experimental Geochemistry and Petrology
• Fluid Induced Mineral Alteration
• Thermodynamic Modeling of Low- and High-Temperature Aqueous Systems
• Field Studies of Granitic Rocks

My general research activities focus on understanding the physicochemical principles that determine mineral stability in the interior of the Earth. This goal is achieved through characterizing, by experimentation and the theory of mineral physics, equilibrium and the kinetics of mineral-melt-fluid systems in the Earth's crust. My research program is grounded in the use of diamond anvil cell assemblies, cold-seal and one-atmosphere furnaces to collect data relevant to pressing geologic questions. Subsequent thermodynamic models provide a means of applying experimental data to ancient and present geologic processes. The core of the research program is outlined below, but experimental studies are conducted in numerous other areas relating to Mineralogy, Petrology and Geochemistry.

Mineral Physics Using Diamond Anvil Cell Assemblies with Synchrotron Radiation
My present research is centered on using diamond anvil assemblies to address problems in mineralogy, petrology and geochemistry. My research group uses the cell together with a synchrotron radiation source (APS, NSLS, CHESS, etc.) to explore the properties of minerals and fluids over a range of crustal conditions (300-1200 K and 0.001-60 GPa). Currently, we are involved in projects addressing the mineral physics of Zircon (pure and doped with rare earth elements), Brucite, Periclase, Fe2S and Fe3S2 (high-pressure compounds stable above 14 GPa), Gold, Platinum and Ice VII. The data obtained will be used to determine PVT equations of state applicable to a number of geophysical and technological problems. The diamond anvil cell assembly can allow my research group to collaborate with faculty in Chemistry (development of equations of state for simple fluids under extreme conditions) and Physics (examination of thermal, chemical, mechanical, electronic properties of both conventional and novel materials at high pressures and temperatures).

Mineral Alteration by a Volatile Phase (± Bacteria Assistance)
I have performed numerous experiments to elucidate the physical chemistry of hydrothermal fluids associated with mineral alteration. The reactions of a high-salinity brine with minerals such as K-feldspar, muscovite, andalusite and quartz are particularly interesting. My research group will continue this research on mineral alteration by expanding the current database to encompass other minerals ubiquitous to the magmatic-hydrothermal regime. Furthermore, I am interested in investigating the role of bacteria on fluid induced mineral alteration. I feel that these studies would be ideal for either undergraduate or M.S. students.

Exchange of Alkali Elements Between Volatile Phases, Minerals and Silicate Melts
The influence of the composition and structure of silicate melts on alkali exchange between a silicate melt and magmatic volatile phase need to be addressed to explore the evolution of the upper continental crust. To this end, we determine equilibrium constants for the exchange of select alkali elements between fluids, minerals and melt and identify the most likely speciation of these alkali elements in a silicate melt. Further, thermodynamic models are developed that can be used to estimate the composition of an exsolved magmatic volatile phase from the composition of ancient plutonic rocks. This model is useful for applications ranging from mineral alteration to metal transport and deposition. This model is in constant refinement by expanding the range of temperature, pressure and composition over which the model is applicable through additional experimentation.

Metal Solubility and Speciation in Minerals, Melts and Magmatic Volatile Phases
I have explored the solubility and speciation of gold in a relatively simple high-temperature, high-salinity sulfur-free liquid at magmatic conditions recently. Saturating the same system with mineral sulfides buffered the fugacity of sulfur species and allowed me to evaluate the relative importance of complexing ligands, e.g. sulfur and chloride, in the transport of metals in a magmatic volatile phase. In a collaboration with Thomas Pettke and Chris Heinrich (Institute of Isotopic Geology and Mineral Resources, ETH Zentrum), I produced synthetic fluid inclusions that were analyzed at ETH Zentrum individually for gold, copper, and iron by using Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry. This collaboration is on-going and will help determine the concentration and speciation of metals over a wide range of magmatic-hydrothermal conditions.