Fe) is adopted as a proxy for planetary composition. This is well grounded for the Sun-Earth system due to the refractory nature of these elements [@Unte16, Supplementary Table \[tab:comparison\]] and has yet to be tested for Venus as there are no definitive measurements of its interior composition or structure. Relative to solar [@Aspl05], the abundances of the major terrestrial planet-building elements Mg, Si, and Fe vary between 10 and 400% of solar in large stellar surveys [e.g. @Adib12; @Bens14; @Hink14; @Brew16]. Variations in stellar (Mg+2Si)/Fe affect an exoplanet’s core mass fraction and the ratio Mg/Si affects the dominant minerals of the silicate mantle. Decreasing Mg/Si will lead to a shift in the dominance of the upper-mantle mineral Mg$_2$SiO$_4$ (olivine), to MgSiO$_3$ (pyroxene), to SiO$_2$ [quartz; @Unte16; @Unte17]. While oxidation state of a planet will affect each of these simple assumptions somewhat, the extent of these oxidation-reduction reactions is a complex function of disk chemistry and the planet’s initial thermal profile and subsequent evolution, each of which are poorly understood areas in exoplanetary science. To first order, though, the assumption that stellar refractory composition roughly mirrors planetary refractory composition provides testable predictions of planetary mass for those planets orbiting stars of 