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Chlorite group mineral group

Chlorite denotes a hydrous phyllosilicate group with a hydroxide interlayer, not a single species or the dissolved chlorite anion. The nomenclature authority distinguishes constituent species by composition and structure. The microbial study used a natural Michigamme, Michigan chlorite preparation with residual magnetite and another unresolved iron-bearing impurity. Its author-assigned ferroan clinochlore identity is retained as specimen context, without converting this group owner into a phase-pure clinochlore or chamosite record. No constituent criticality designation is inherited.

Microbial & Biochemical Mechanisms (1)

MR-1 reduction of iron associated with a natural chlorite preparation

redox transformation Microbial

Associated Organisms: Shewanella oneidensis MR-1 (NCBITaxon:211586)

Washed Shewanella oneidensis MR-1 suspensions increased iron(II) in a weak-acid-extractable fraction relative to uninoculated controls. Bulk Mössbauer fits support reduction of chlorite-associated iron(III), alongside unresolved impurity contributions. Most reduced iron remained associated with solids; small aqueous iron increases and greater susceptibility to a later acid extraction do not establish isolated-metal recovery.

Experimental Context & Analytical Limits:
Laboratory resting-cell bottles contained chlorite powder smaller than 100 micrometres, prepared by abrasion, hand picking and sieving of a Michigamme metamorphic specimen, at a 1:40 solid-to-solution mass ratio. The anaerobic medium was 30 mM bicarbonate at pH 7 under 80% nitrogen and 20% carbon dioxide, with 10 mM lactate and, in selected bottles, 10 micromolar AQDS. MR-1 was precultured at 30 degrees C, harvested and washed twice; the inspected main and supplement do not explicitly give the resting-assay temperature or final cell density. Residues were collected after 28 days. Figure 1 reports standard errors of triplicate measurements, without clearly establishing independent culture replication. The separate eight-week growth experiments used biotite flakes and are not chlorite growth evidence.
Curated Evidence Points:
Figure 1B shows elevated weak-acid-extractable Fe(II) with MR-1, with and without AQDS, relative to uninoculated controls. The denominator is total iron extracted by 0.5 N HCl for one hour, not all structural iron or a recovery yield. Figure 2C-D and Table 2 show a decrease in fitted chlorite Fe(III) area from 10.4% to 8.2%; the authors interpret this as about 21% of the starting chlorite Fe(III) reduced. These are spectral component estimates, not a mineral mass balance. AQDS accelerated early reduction without a clear increase in its final extent.
Methods explicitly retain magnetite below the XRD detection limit, and Mössbauer fits include magnetite plus an unresolved impurity. The paper calls the chlorite Fe-rich clinochlore although its calculated formula is Fe-dominant; no new species assignment or quantitative purity is inferred. Figure 1D shows aqueous iron changes, but peak timing in the AQDS curve differs from the prose. ICP-AES measures elemental iron rather than independently establishing dissolved oxidation state. Figure 3 is a subsequent 0.5 M HCl extraction, not culture-only dissolution. The proposed long-distance electron-transfer pathway remains interpretive; no molecular perturbation proves it.
Supplemental Figure S2 establishes the initial source-assigned ferroan clinochlore diffraction pattern. Figures S1 and S2 are explicitly unaltered powders and do not display a before/after XRD comparison, although the main text cites them when reporting no appreciable structural change or new phases. Main microscopy and the source interpretation support predominantly solid-associated reduction with that evidential limit. Figure S3 and the growth/counting methods concern biotite only. No industrial process, isolated iron product or complete phase-specific reduction follows.

Sources & References

  1. ima_compendium_2019: Schertl, Mills and Maresch, editors (2019 copyright). A Compendium of IMA-Approved Mineral Nomenclature, prepared for IMA2018. PDF p34 reproduces Whitney and Evans (2010), Abbreviations for names of rock-forming minerals, DOI 10.2138/am.2010.3371; Table 1 marks chlorite and illite GROUP. Historical nomenclature table, not a 2026 species approval.
    https://cnmnc.units.it/ima_reports/2%20IMA-Nomenclature-e-Booklet-2019-1.pdf (accessed 2026-10-14)
  2. guggenheim_2006: Guggenheim et al. (2006). Summary of recommendations of nomenclature committees relevant to clay mineralogy: report of the AIPEA Nomenclature Committee for 2006. Clays and Clay Minerals 54:761-772. DOI 10.1346/CCMN.2006.0540610; Table 2 and pp765-766 chlorite group, subgroups and dominant-cation naming.
    https://cnmnc.units.it/ima_reports/claynomenclature.pdf (accessed 2026-10-14)
  3. brookshaw_2014: Brookshaw, Lloyd, Vaughan and Pattrick (2014). Bioreduction of biotite and chlorite by a Shewanella species. American Mineralogist 99:1746-1754. DOI 10.2138/am.2014.4774CCBY. Complete original; Methods pp1747-1748, Figures 1-5, Tables 1-2 and Discussion.
    https://doi.org/10.2138/am.2014.4774CCBY (accessed 2026-10-14)
  4. brookshaw_2014_si: Brookshaw et al. (2014), deposit AM-14-801, 4774Supplemental.pdf, three pages. Culturing methods and Figures S1-S3, including the unaltered chlorite XRD pattern in S2. Linked archive filename BookshawAM-14-801.zip retains the depositor spelling.
    http://www.minsocam.org/MSA/AmMin/TOC/2014/AS2014_Data/BookshawAM-14-801.zip (accessed 2026-10-14)
  5. ncbi_mr1: NCBI Taxonomy 211586, Shewanella oneidensis MR-1, strain; current taxonomy XML inspected 14 October 2026.
    https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?id=211586&mode=Info (accessed 2026-10-14)

Curation History

Timestamp Curator Action Summary
2026-10-14T16:33:06.562206+00:00 codex (GPT-6; codex) CREATE Created chlorite-group owner from complete primary microbial experiments with explicit source, phase and assay limitations.

Record source: data/records/chlorite.yaml