 Spectral modeling in 2007 identified a key deposit in Nili Fossae dominated by a single mineral phase that was spatially associated with olivine outcrops.The dominant mineral appeared to be magnesite, while morphology inferred with HiRISE and thermal properties suggested that the deposit was lithic.Stratigraphically, this layer appeared between phyllosilicates below and mafic cap rocks above, temporally between the Noachian and Hesperian eras.