Synthesis of Critical Element-bearing Olivine and Pyroxene

Abstract Nickel (Ni) and cobalt (Co) are critical elements necessary for the transition to carbon-free energy generation. Increasing global demand for these elements requires new sources to be found. Both Ni and Co are found in low concentrations in mafic and ultramafic silicate minerals. To systematically understand the partitioning behavior of these elements in silicate minerals and to provide starting materials for experiments, we synthesized forsterite and enstatite with Ni and Co contents between 1.2 and 8.6 wt.%. We find that >95% purity syntheses of large batches (tens of grams) of both minerals are possible and that purity decreases with increasing Ni or Co dopant levels in enstatite syntheses. Impurities in forsterite syntheses include cristobalite and enstatite, while impurities in enstatite syntheses include cristobalite and forsterite. Partitioning of Ni and Co dopants favors forsterite over enstatite, with a more pronounced effect observed in Ni than Co. The doped minerals serve as starting materials for experiments that seek to extract critical elements from ultramafic and mafic rocks, in which the primary carriers of Ni and Co are olivine and pyroxene.