A heavy dust fell in Beijing on April [16][17] 2006. The dust storm formed in middle and western Inner Mongolia, China, under a strong Mongolian Cyclone. During the dust fall, the near-surface wind speed was insignificant in Beijing. The minimal wind speed at ground level indicates that the dust must have been transported by upper northwestern winds, and the local dust of Beijing contributed little to dust fall. The lack of a contribution from local dust differed from previous dust fall events in Beijing. Therefore, this dust fall provides good information on the dust source. Dust samples colleted during this event and Pleistocene loess samples from the Beijing area were analyzed for magnetic susceptibility, bulk particle and quartz grain size distributions, bulk particle and quartz micro-textures, mineralogy, carbonate content, major element concentrations, trace element and rare earth element (REE) concentrations, and the oxygen isotope composition of quartz. The results indicate the following. (1)