Previous studies suggest that interactions between dust particles and clouds are significant; yet the conditions where dust particles can serve as cloud condensation nuclei (CCN) are uncertain. Since major dust components are insoluble, the CCN activity of dust strongly depends on the presence of minor components. However, many minor components measured in dust particles are overlooked in cloud modeling studies. Some of these compounds are believed to be products of heterogeneous reactions involving carbonates. In this study, we calculate with diameters between about 0.6 and 2 µm under some conditions. Dust particles > 2 µm often activate regardless of their composition. Only under very specialized conditions does the addition of a dust distribution into a rising parcel containing fine (NH 4 ) 2 SO 4 particles significantly reduce the total number of activated particles via water competition. Effects of dust on cloud saturation and droplet number via water competition are generally smaller than those reported previously for sea salt. Large numbers of fine dust CCN can significantly enhance the number of activated particles under certain conditions. Improved representations of dust mineralogy and reactions in global aerosol models could improve predictions of the effects of aerosol on climate.