University of Chicago Graduate Student Levke Kööp, her co-advisor Robert A. Pritzker Associate Curator Philipp Heck and colleagues from Germany are authors on an article on 4.6-billion-year old metal nuggets in the journal Geochimica and Cosmochimica Acta. These micro-nuggets made of rare metals like iridium and tungsten are found inside the oldest minerals (hibonites and spinels) that formed in the Solar System. In contrast to previous studies, which separated the refractory metal nuggets (RMNs) from their hosts by dissolution, the international team studied a large number of nuggets still embedded in their host minerals (as in the electron microscope image at left), which allowed an investigation of the relationship between the nuggets and their hosts. The team found that nuggets only occur in hosts that show evidence for melting, suggesting that nugget formation may be linked to melting processes in the early Solar System. The research is part of Daniel Schwander (Johannes Gutenberg-Universität, Mainz, Germany) and Levke’s dissertation projects. Levke identified the nuggets inside the Murchison meteorite from the Field Museum collection, which she prepared for analysis in the Robert A. Pritzker Center’s Cosmochemistry Laboratory and identified the nuggets using scanning electron microscopes and X-ray spectroscopy at The Field Museum and the University of Chicago. The article is available online.