Archean komatiites are the hottest magmas preserved on Earth and are thus unique probes of its thermal evolution. Estimating their eruption temperatures remains problematic, however, because the uppermost (A1, A2) zones of komatiite flows contain randomly oriented spinifex-textured olivines, indicative of rapid cooling and growth. ; This work was made possible by an Australian Postgraduate Award and ANU Vice Chancellor’s Scholarship to PAS and an Australian Research Council Discovery grant, DP130101355, to HO’N.