The mechanism of the low salinity EOR process in sandstone reservoirs has been debated in the literature for more than a decade. We recently proposed a chemical wettability alteration mechanism for the process, well founded in experimental observations showing that the increase in pH as the high saline water is displaced by the low saline water is a key factor. Even though this chemical understanding is quite well described, there are parameters/factors that can disturb the main process like the following: combinations of certain minerals, temperature, salinity, and composition of formation water could have impact on the low salinity EOR processes. Plagioclase, a polysilicate mineral, which is often present in sandstone reservoir rock, can have a significant effect on the initial pH of the formation water, which will influence the initial wetting condition. In this experimental work, it is shown that the presence of plagioclase in reservoir rock and outcrop material responded differently on the low salinity EOR-effect. The experimental results are discussed in relation to the previously published chemical mechanism for the low salinity EOR process, where changes in pH are believed to promote the wettability alteration of the rock.