There is a scatter plot on exactly this in the background story linked in TFA [0]. B and Be come out on top, both with around 10 times the mass density and 3 ti

There is a scatter plot on exactly this in the background story linked in TFA [0]. B and Be come out on top, both with around 10 times the mass density and 3 times the volume density of Fe. [0]: https://doi.org/10.1016/j.pecs.2018.05.001 https://doi.org/10.1016/j.pecs.2018.05.001