Aluminosilicate glasses are highly important in the glass manufacturing industry where they are used to make products that include the touch screens for cell phones and tablets. Here, the glass properties are controlled by adding network modifiers such as Mg. However, little is known about the way in which Mg effects the glass structure, so little is known about the mechanisms of plastic deformation when cover glass is scratched. We will use neutron diffraction to elucidate the structural role of Mg in aluminosilicate glasses. The results will be combined with those obtained from other experimental techniques to build realistic structural models for understanding the mechanical response of these materials to sharp contact loading.