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Cobalt-rich ferromanganese crusts primary resource

Naturally occurring layered iron-manganese oxide and oxyhydroxide deposits on exposed marine rock surfaces, commonly seamounts. This resource identity covers the cobalt-bearing, predominantly hydrogenetic crusts formed by accumulation from seawater; it does not denote every hydrothermal encrustation. The heterogeneous crust material is distinct from sediment-hosted polymetallic nodules, constituent cobalt or manganese elements, a pure mineral species, and a processing residue. Maciąg et al. characterize crusts and their altered basalt interfaces from Dirck Hartog Ridge; their sample-specific mineral mixtures are not a universal formula or grade. Collection and physical preparation do not make this geological resource secondary. The laboratory mechanism below records conditional redistribution of cobalt and nickel in whole-crust microcosms; it does not establish a specific receiving phase, a purified metal product or industrial deployment. The resource inherits no constituent criticality.

Microbial & Biochemical Mechanisms (1)

Community-associated cobalt redistribution in natural crust microcosms

other Microbial

Unpoisoned whole-crust microcosms containing indigenous microbial communities showed a decline in aqueous cobalt between days 30 and 50, with treatment-dependent nickel behavior. The paper interprets the decline as sorption, but it is calculated indirectly from the solution difference. This entry uses process other because the experiment does not separately identify adsorption to cells or minerals, cellular absorption, or precipitation. The sodium-azide comparison and cell observations support a community association, while altered control chemistry prevents assigning the entire difference to microbial activity. Neither cobalt oxidation nor nickel reduction, a specific product mineral, or isolated-metal recovery is established.

Experimental Context & Analytical Limits:
Natural hydrogenetic Fe–Mn crust fragments from Afanasiy–Nikitin Seamount, collected in 2009 at 2204 m, were broken by hammering, gently rinsed in bottom water and stored at 4°C in filtered/autoclaved ambient water. Approximately 1 g of crust with its unresolved resident community was incubated in 10 mL sterile seawater in 15-mL screw-capped tubes, with or without 0.1% glucose. Table 1 specifies triplicate tubes, four crust-free blank formulations and two 15 mM sodium-azide crust controls. Incubations were dark, at 4±1°C and nominally 28°C, for 30 and 50 days; Methods gives 28±1°C whereas Table 1, abstract and Results give 28±2°C. No pressure-controlled incubation is reported for this experiment. Co and Ni in the supernatant after 5009 g centrifugation for 10 min at 4°C were measured by adsorptive stripping voltammetry with ammonia buffer and dimethylglyoxime, then normalized to dry crust mass. Total cell counts after sonication are not a viability-specific assay. The separate 20 MPa study used a different collection site/depth, 0.01% glucose and additional autoclaved-crust controls; its controls, taxa and performance cannot be transferred to these tubes.
Curated Evidence Points:
Methods pp.1159–1160 and Tables 1–2 support the narrow laboratory observation: day-30-to-day-50 aqueous Co depletion was reported for the unpoisoned crust arms; glucose-amended poisoned controls instead released Co over that interval. Unamended poisoned controls also showed Co depletion, so retention is not exclusively biological. This is an indirect interval-specific solution endpoint, not a measured increase in total solid cobalt or a recovery percentage.
Table 2 retains counterevidence to blanket microbial metal enrichment: at 4°C without glucose, reported Ni sorption was 1.89 µg/g dry crust in the biotic arm versus 20.96 µg/g in the azide arm; at 28°C the unamended biotic arm released Ni while the azide arm sorbed it. Glucose-amended biotic and poisoned arms both released Ni. The Results sentence claiming Ni sorption only in biotic incubations conflicts with Table 2 and the Discussion. Table 3 gives a nonsignificant temperature term for glucose-amended Co (P=0.736), despite discussion wording about temperature dependence. These source inconsistencies prevent a universal microbial advantage or temperature-response claim.
Results p.1161 defines final sorption from the difference between days 30 and 50, while the preceding equation labels initial-minus-final aqueous concentration as metal released. This sign/endpoint wording and unavailable underlying supplemental data prevent independent reconstruction of reported amounts. Blank formulations are listed, but their complete outcomes and the blank-correction procedure were not established. Figures 2–4 were not visually inspected; captions describing cell-like, EPS-like and secondary-mineral-like structures cannot identify a receiving metal phase or enzyme. Direct chemical effects of azide, mineral sorption and precipitation remain competing explanations. No quantitative Co amount, mineral-specific yield or industrial application is adopted.
Methods pp.2,4–5 locate this companion experiment at 1987 m and explicitly add autoclaved-crust controls because sodium azide may chemically interfere with crust metals. Its 20 MPa pressure bags, 0.01% glucose and 24–82-day schedule differ from the focal tube study. The papers share a research program and thesis background, but their reported sample provenance and protocols differ; they are not pooled as independent replications of the same assay. The companion study supplies an explicit control caveat, not missing matched controls for the focal study.

Sources & References

  1. usgs2025: U.S. Geological Survey (2025). U.S. Geological Survey Global Seabed Mineral Resources. Fact Sheet 2025–3017, version 1.1, April 2025; page 2, Table 1 distinguishes rock-surface cobalt-rich ferromanganese crusts from abyssal-sediment polymetallic nodules. Constituent asterisks refer to the U.S. 2022 critical-mineral list, not a criticality designation for the resource. Previously acquired official PDF re-inspected.
    https://pubs.usgs.gov/fs/2025/3017/fs20253017.pdf (accessed 2026-10-11)
  2. maciag2019: Maciąg, Zawadzki, Kozub-Budzyń, Piestrzyński, Kotliński and Wróbel (2019). Mineralogy of Cobalt-Rich Ferromanganese Crusts from the Perth Abyssal Plain (E Indian Ocean). Minerals 9(2):84. DOI 10.3390/min9020084. Primary 33-page paper; Introduction, Methods 3, Results 4.1–4.2, Table 1 and Figures 2–4 establish geological substrate and heterogeneous material identity; no microbial assay is inferred.
    https://doi.org/10.3390/min9020084 (accessed 2026-10-11)
  3. sujith2017cobalt: Sujith, Ramanan, Gonsalves and LokaBharathi (2017). Microbial activity promotes the enrichment of cobalt over nickel on hydrogenetic ferromanganese crusts. Marine Georesources & Geotechnology 35(8):1158–1167. DOI 10.1080/1064119X.2017.1298169. Author-posted full text and PDF text, Methods pp.1159–1160, Results pp.1161–1163 and Tables 1–3 inspected. Figure captions were read, but visual plots and supplemental Tables S1–S4 were unavailable to this curation; no figure-derived values are imported.
    https://doi.org/10.1080/1064119X.2017.1298169 (accessed 2026-10-11)
  4. sujith2017pressure: Sujith, Gonsalves, Bhonsle, Shaikh and LokaBharathi (2017). Bacterial activity in hydrogenetic ferromanganese crust from the Indian Ocean: a combined geochemical, experimental and pyrosequencing study. Environmental Earth Sciences 76:191. DOI 10.1007/s12665-017-6495-y. Publisher identity and author-posted Methods pp.2,4–5 inspected for sample/experiment separation and explicit sodium-azide interference caution; pressure-study performance and taxon functions are not imported.
    https://doi.org/10.1007/s12665-017-6495-y (accessed 2026-10-11)

Curation History

Timestamp Curator Action Summary
2026-10-11T12:40:14.873373+00:00 codex (GPT-6; codex) CREATE Created the distinct natural marine crust resource identity from official USGS guidance and primary mineralogical characterization; deferred incompletely reviewed microbial mechanisms and inherited criticality.
2026-10-11T13:48:09.902989+00:00 codex (GPT-6; codex) EDIT Added a qualified whole-crust community-associated cobalt redistribution observation from Sujith et al. 2017, retaining nickel counterevidence, azide confounding, indirect endpoints and source/access limitations; preserved material identity and prior provenance.

Record source: data/records/cobalt-rich-ferromanganese-crusts.yaml