The Rock Abrasion Tool (RAT) magnet experiment on the Mars Exploration Rovers was designed to collect dust from rocks ground by the RAT of the two rovers on the surface of Mars. The dust collected on the magnets is now a mixture of dust from many grindings. Here the new data from the experiment are presented. The findings from Mars are furthermore compared to simulation experiments performed on Earth. New experiments with analog rocks that mainly contain hematite indicate the likely presence of a stronger magnetic phase besides hematite in the outcrop rock formations found on Meridiani Planum, a phase which was hitherto not detected by other measurements (such as Mossbauer) on these rocks.