The aqueous dissolution rate is a key indicator of a portland cement's reactivity, and is relevant in predicting the progress of reactions and property development in cementitious materials. Though a valuable material property, the dissolution rates of the individual cement phases and their mixtures have been seldom determined. This work for the very first time applies vertical scanning interferometry (VSI) as a new method, aptly suited to measure dissolution dynamics of cement relevant minerals. Special emphasis is placed on measuring the first dissolution rate (DRF), i.e., when water initially and for a short duration (i.e., on the order of tens of seconds) contacts the mineral surface. DRF, molm-2s-1) are measured for a variety of fast and slower dissolving minerals including (1a) natural limestone (CaCO3), (1b) reagent-grade gypsum (CaSO42H2O); (2) alite (impure, MIII-Ca3SiO5); and (3) an ASTM C150, Type I/II ordinary portland cement across a range of solution pHs. Detailed aspects of image acquisition, processing and interpretation are presented to emphasize the methodological and statistical treatment of the results. The outcomes develop quantifications of aqueous dissolution ratesinputs valuable in simulating cement hydration, and forward a new means to study correlations between chemical composition, crystallography, and the reactivity of cementitious materials.