Ramsdellite mineral
Ramsdellite is the orthorhombic MnO2 mineral species listed as grandfathered in the September 2026 IMA list, with original-description year 1943. That year is not an approval accession. It is distinct from pyrolusite, elemental manganese, unspecified manganese dioxide and fungal birnessite. The experiment below used a chemically synthesized powder assigned to ramsdellite by XRD; it does not establish microbial production of ramsdellite. No manganese or cobalt commodity criticality designation is inherited by this mineral.
Microbial & Biochemical Mechanisms (1)
Abiotic cobalt sorption by chemically synthesized ramsdellite-assigned powder
other
The chemically prepared Mn oxide removed cobalt from a buffered synthetic solution. Solid-state surface spectra and extraction were interpreted as adsorption with oxidation of part of the retained cobalt; they do not determine a unique crystallographic incorporation site or a pure recovered cobalt phase. This arm contained no microbial biomass. The separately prepared fungal birnessite comparator belongs to a different mineral record and does not make this reaction microbial.
Experimental Context & Analytical Limits:
Sasaki et al. produced the comparator by adding ammonium peroxodisulfate to boiling MnSO4 solution, cooling, filtering and freeze-drying. Figure 1b assigns its four distinct XRD peaks to ramsdellite (JCPDS 7-222); no quantitative phase refinement or purity fraction is supplied. The powder contained 54.1 wt% Mn and had BET area 11.3 m2/g. Sorption used 0.015 g synthetic powder in 0.150 L Co(NO3)2 solution, reported as approximately 1 mM solid Mn, with 100 mM KNO3 and PIPES at initial pH 6.5. Flasks were rubber-stoppered and shaken at 25 degrees C and 100 rpm; Section 3.2 says duplicate runs. Section 2.3 describes 100-300 h, while Figure 7 extends beyond 300 h. Samples passed through 0.2-micrometre filters for elemental Co/Mn analysis by AAS and ICP-MS; the solution measurements do not directly speciate cobalt valence. Collected solids were air-dried for a week at 4 degrees C before surface analysis. The laboratory reagent experiment establishes neither treatment of an actual industrial stream nor isolated metal-product recovery.
Sasaki et al. produced the comparator by adding ammonium peroxodisulfate to boiling MnSO4 solution, cooling, filtering and freeze-drying. Figure 1b assigns its four distinct XRD peaks to ramsdellite (JCPDS 7-222); no quantitative phase refinement or purity fraction is supplied. The powder contained 54.1 wt% Mn and had BET area 11.3 m2/g. Sorption used 0.015 g synthetic powder in 0.150 L Co(NO3)2 solution, reported as approximately 1 mM solid Mn, with 100 mM KNO3 and PIPES at initial pH 6.5. Flasks were rubber-stoppered and shaken at 25 degrees C and 100 rpm; Section 3.2 says duplicate runs. Section 2.3 describes 100-300 h, while Figure 7 extends beyond 300 h. Samples passed through 0.2-micrometre filters for elemental Co/Mn analysis by AAS and ICP-MS; the solution measurements do not directly speciate cobalt valence. Collected solids were air-dried for a week at 4 degrees C before surface analysis. The laboratory reagent experiment establishes neither treatment of an actual industrial stream nor isolated metal-product recovery.
Curated Evidence Points:
Support
Source:
sasaki2008
Sections 2.1-2.3 and 3.1, Figures 1-6, establish the chemically synthesized comparator and its distinct phase, composition, morphology and surface properties. Figure 7b and Section 3.2 show a cobalt concentration decrease to approximately 0.15 mM within less than 24 h, followed by broadly stable residual concentrations. Figure 8b compares Mn release with and without cobalt; the additional release attributed to cobalt is small. This is filter-passing solution depletion with retained cobalt detected on solids, not a quantified isolated-product yield or a manganese extraction process.
Partial
Source:
sasaki2008
Figures 9b and 10b support the authors' surface-spectroscopic interpretation of predominantly Mn(IV) and oxidized sorbed cobalt. Co 2p overlaps the Mn 2s background, and their fitted surface Co/Mn ratio is not a whole-powder composition. Section 3.2 reports a CuSO4-exchangeable Co(II) fraction in both powders, so complete conversion of retained cobalt to Co(III) is unsupported. Figure 11 uses a difference between the with-Co and no-Co Mn curves to infer electron-acceptor behavior; it does not directly measure bulk Mn valence changes or locate cobalt in ramsdellite lattice sites.
Partial
Source:
sasaki2008
Numerical reporting limits prevent a reproducible capacity claim. Section 2.3 gives an upper feed concentration of 175 micromol/L, but Figure 7 starts near 0.21 mM and Section 3.2 separately mentions 0.55 mM. The printed 28.7 mmol-Co/mol-solid-Mn capacity and 5.6-fold comparison are not reconciled with the Figure 7 concentration change and nominal solid-Mn loading; they are not adopted as validated performance values. The preparation paragraph prints 18.2 mol/L MnSO4 and peroxodisulfate, and the sorption paragraph prints a 500 dm3 flask; these unusually large values are retained as unresolved source recipe/unit concerns rather than silently corrected or treated as verified protocols. No no-sorbent time-course blank is displayed. The fungal-tissue-only control shows no appreciable cobalt uptake under this assay, but is not a ramsdellite-matched control.
Context_only
Source:
sasaki2008
The fungal material is source-assigned poorly crystalline birnessite, containing retained organic material and having a larger BET area (81.4 m2/g). Phase, area, pore structure, composition and biomass differ simultaneously from the ramsdellite comparator. Its larger cobalt uptake therefore cannot isolate biological origin as the cause. Neither that comparison nor the fungus's production of birnessite demonstrates microbial ramsdellite formation, metabolism during the abiotic arm or industrial deployment.
Sources & References
-
ima_2026_09: IMA-CNMNC. The New IMA List of Minerals, September 2026. PDF page 182, Ramsdellite row; pages 1-2, field definitions and distribution terms.
https://cnmnc.units.it/files/editor/IMA_Master_List_(2026-09).pdf (accessed 2026-10-14) -
ramsdellite_handbook: Handbook of Mineralogy, Ramsdellite. Mineral Data Publishing, version 1 (2001-2005); one-page mineral entry, crystal data and polymorphism.
https://www.handbookofmineralogy.org/pdfs/ramsdellite.pdf (accessed 2026-10-14) -
sasaki2008: Sasaki, Matsuda, Urata, Hirajima and Konno (2008). Sorption of Co2+ Ions on the Biogenic Mn Oxide Produced by a Mn-Oxidizing Fungus, Paraconiothyrium sp. WL-2. Materials Transactions 49(3):605-611. DOI 10.2320/matertrans.M-MRA2007888. Sections 2-3 and Figures 1-11; synthetic ramsdellite comparator, not the fungal product.
https://doi.org/10.2320/matertrans.M-MRA2007888 (accessed 2026-10-14)
Curation History
| Timestamp | Curator | Action | Summary |
|---|---|---|---|
2026-10-14T07:22:08Z |
codex (GPT-6; codex) | CREATE | Created ramsdellite identity and explicitly abiotic cobalt-sorption evidence; preserved measurement, source inconsistency and comparator limitations. |
Record source: data/records/ramsdellite.yaml