Matter flung out into space during black hole-neutron star mergers may well be one of the major contributors to the “r-process” heavy-elements in the universe such as gold and lead. To test this idea, we calculated the nuclear reactions taking place in the ejected matter from our black hole-neutron star mergers using the “SkyNet” nucleosynthesis code written by SXS member Jonas Lippuner. Our first studies found that it is very easy for our ejecta to produce the high-mass r-process elements (in abundance ratios not terribly different from what’s in the sun), but very little of the low-mass r-process elements are made, meaning they would have to come from a different source. We then found that this underproduction can be ameliorated (but not removed) by the effect of neutrinos given off by the merger remnant being absorbed by the outgoing matter, which changes its composition. Read the paper here [arXiv:1601.07942].