• Trevorite: Ni-rich spinel formed by metasomatism and desulfurization processes at Bon Accord, South Africa?

      O'Driscoll, Brian; Clay, Patricia L.; Cawthorn, R. Grant; Lenaz, Davide; Adetunji, Jacob; Kronz, Andreas; Keele University; University of Manchester; University of the Witwatersrand; Trieste University; et al. (Mineralogical Society, 2014-02-01)
      The 3.5 Ga Bon Accord Ni deposit occurs within the lowest serpentinized mafic ultramafic lavas of the Barberton Greenstone Belt (South Africa). Though now completely mined out, it comprised a suite of rare Ni-rich minerals that led to its interpretation as either an extraterrestrial body or as an oxidized fragment of Fe-Ni alloy originating from the terrestrial core. In this study, we draw on detailed petrographic observation and mineral chemical data, as well as previous work, to re-evaluate these ideas. The balance of evidence, from thin section (<1 mm) to regional (∼10s of km) scales, appears to support an alternative origin for Bon Accord, possibly as an oxidized Ni-sulfide deposit formed in association with ocean floor komatiite eruptions.