High-pressure experimental techniques create the extreme physical environments necessary to explore properties of materials relevant to Earth and other planetary bodies. The diamond-anvil cell is a versatile device capable of achieving both static and dynamic compression at a range of temperatures. Szomolnokite, a hydrous iron-sulfate, is an endmember of an extensive mineral group observed on Earth, Mars, and the icy satellites. I present a culmination of diamond-anvil cell work utilizing synchrotron radiation to measure the structural, vibrational, and electronic properties of szomolnokite at previously unstudied combinations of pressure and temperature. Using X-ray diffraction, and synchrotron Mössbauer and infrared spectroscopy, I identify two crystal structural phase transitions characterized by Fe-octahedral site distortion and potentially reversible behavior upon decompression. These results support this mineral’s ability to retain water within deep planetary interiors and upon recycling back to the surface.
