The hydrothermal laboratory contains equipment to reproduce the pressures and temperatures existing to mid-crustal depths. It contains two extraction-quench sampling bombs which permit withdrawal of solution during the progress of a run to pressures of 3 kbar and 750 oC. These are used extensively to determine mineral solubilities in crustal fluids. There are also 10 cold-seal reaction vessels capable of 4 kbar at 700 oC to look at mineral-mineral transformations in the crust and undertake mineral synthesis reactions. Also available are 1 atm furnaces that can be used to temperatures of 1400 oC.