An experimental system for measuring ion-beam-induced deposition yield is described. Gold films were deposited on quartz-crystal microbalances (QCM) by decomposing dimethyl gold hexafluoroacetylacetonate molecules (C 7H7F6O2Au) with a 5-keV argon-ion beam. The QCMs provide an in situ measurement of the deposition rate as a function of ion dose, dose rate, gas pressure, and substrate temperature. The deposition yield, or mass deposited per incident ion, is shown to increase with increasing pressure and decreasing temperature. The yield is independent of the ion dose rate, which implies that the deposition process is not due to macroscopic heating. The deposition yield is shown to depend on the sputter yield of the substrate. The density of the deposited films was determined to be about 10 g/cm3, which is about half the density of bulk gold (19.3 g/cm3). The difference in density is due to carbon contamination in the deposited films.