{"doi":"10.1016/j.icarus.2021.114471","title":"Manganese oxides in Martian meteorites Northwest Africa (NWA) 7034 and 7533","abstract":"We report the discovery of indigenous Mn-oxides in Martian regolith breccias Northwest Africa (NWA) 7034 and 7533. These Mn-oxides occur in Mn-rich regions as nanocrystals mixed with silicates, FeOOH, and possible phosphates. The Mn-rich regions contain up to 34 wt% Mn and typically display large chemical gradients on the scale of 10–20 μm. The Martian origin of Mn-oxides was established by the presence of Mn-rich glass (4.8–5.6 wt% Mn) in the fusion crust that crosscuts a Mn-oxides-bearing monzonite clast and by the absence of Mn-oxides on the environmentally exposed surfaces (exterior and fractures) of the meteorites. Manganese K-edge X-ray absorption spectrum (XAS) of the Mn-rich glass in the fusion crust indicated that this glass included high-valent Mn species. Synchrotron micro-X-ray diffraction of a Mn-rich region in a basalt clast and XAS of Mn-rich regions in three monzonite clasts indicate Mn-oxides in these regions are dominantly hollandite-structured with 67–85 mol% of the total Mn being Mn4+. The fact that Mn-rich regions are present in diverse petrological associations but are absent in the matrix of the breccias indicates that the Mn-oxides formed through surface alteration prior to the final brecciation event that assembled NWA 7034 and 7533. Thus, the age of the Mn-oxides is older than the lithification age (arguably 1.35 Ga) of NWA 7034 and 7533. Together with findings of Mn-rich phases within Noachian and Hesperian sedimentary strata in Endeavour and Gale craters, our results suggest that Mn-oxides are a common weathering product on Mars, suggesting aqueous environment on the Martian surface with high redox potential.","journal":"Icarus","year":2021,"id":179367,"datarank":0.0,"base_score":0.0,"endowment":0.0,"self_citation_contribution":0.0,"citation_network_contribution":0.0,"self_endowment_contribution":0.0,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":18,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9654,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2021-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":668323,"name":"Woodward W. Fischer","orcid":"0000-0002-8836-3054","position":1,"is_corresponding":false},{"id":726807,"name":"Chi Ma","orcid":"0000-0002-1828-7033","position":2,"is_corresponding":false},{"id":726808,"name":"J. R. Beckett","orcid":"0009-0007-7092-8110","position":3,"is_corresponding":false},{"id":726809,"name":"Oliver Tschauner","orcid":"0000-0003-3364-8906","position":4,"is_corresponding":false},{"id":726810,"name":"Yunbin Guan","orcid":"0000-0002-7636-3735","position":5,"is_corresponding":false},{"id":668314,"name":"Usha Lingappa","orcid":"0000-0001-5691-6788","position":6,"is_corresponding":false},{"id":312253,"name":"Samuel M. Webb","orcid":"0000-0003-1188-0464","position":7,"is_corresponding":false},{"id":726811,"name":"Vitali B. Prakapenka","orcid":"0000-0001-9270-2330","position":8,"is_corresponding":false},{"id":668316,"name":"N. Lanza","orcid":"0000-0003-4445-7996","position":9,"is_corresponding":false},{"id":727717,"name":"C. B. Agee","orcid":null,"position":10,"is_corresponding":false},{"id":726806,"name":"Yang Liu","orcid":"0009-0004-6019-2267","position":0,"is_corresponding":true}],"reference_count":98,"raw_metadata":null,"created_at":"2026-07-18T23:47:48.974996Z","pmid":null,"pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}