\[fig:histogram\] and \[fig:rocktype\] for the @Adib12 dataset (black) and *Kepler* hosts (red). Open symbols are those buoyancy forces calculated from the relationship between stellar \[Na/Si\] and $F_{c}$ (Equation \[eq:fit\], Supplementary Figure \[fig:fit\]) for the @Adib12 stars (squares) and *Kepler* hosts (circles). The 1063 stars in the stellar survey of @Adib12 show $\sim$2.5 orders of magnitude difference in total Na, halving or doubling $\delta _{\rm {Na}}$ from the Solar value represents the entire sample either producing none and all plates being negatively chemically buoyant. The index (Mg+2Si)/Fe is both a primary control on the compositional extent of the thermodynamic database [@Ghio02] as well as defining the approximate proportions of core and mantle of an associated terrestrial planet [@Unte16]. []{data-label="fig:Sodium"}](Sodium.pdf){width="\linewidth"}

when \[Na/Si\] is scaled from @Aspl05 (Supplementary Figure \[fig:fit\]), 78% of the variation in $F_c$ can be explained by variation in \[Na/Si\]. For a given stellar \[Na/Si\] value, 95% of $F_c$ values fall within $\pm10^{12}$ N m$^{-1}$, which is a more complex function of the refractory element composition of the planet and must be derived through the methods outlined here. This correlation between $F_c$ and Na abundance allows us to estimate the chemical buoyancy of the 454 stars in the @Adib12 dataset 