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Dolomite mineral

Dolomite is the calcium-magnesium carbonate mineral CaMg(CO3)2. The IMA-CNMNC September 2026 list gives grandfathered status G and original-description year 1792, not a numbered approval identifier. This owner denotes the mineral species, distinct from dolostone rock, the dolomite mineral group, Mg-bearing calcite, compositionally similar disordered precursors, and elemental magnesium. A laboratory mixed-biofilm study reports dolomite with detectable ordering reflections in an anoxic illuminated Mn-amended treatment; neither all Mg-rich carbonate precipitates nor all mineral samples are thereby identical. No criticality designation is inherited from a constituent.

Microbial & Biochemical Mechanisms (1)

Dolomite precipitation in Mn-amended anoxygenic photosynthetic biofilms

biomineralization Microbial

Mixed anoxic biofilms enriched from Fayetteville Green Lake sediments produced a carbonate phase assigned to dolomite with detectable ordering in the illuminated, 1 mM Mn(II)-amended treatment. Original supplementary XRD compares this treatment with a dolomite standard, illuminated cultures without added Mn and dark cultures with Mn. Supplementary microscopy shows cell-associated mineral encrustation and mineral grains on extracellular polymeric substances. The authors infer a role for active anoxygenic photosynthetic cell surfaces together with EPS and Mn; the molecular action of Mn and a unique organism's causal contribution remain unresolved.

Experimental Context & Analytical Limits:
Laboratory serum-bottle enrichment, 27°C, 12 h light/12 h dark cycle and two-week comparison; sulfide-reduced modified FGL medium with approximately 2 mM Mg, 1 mM Ca, 44 mM bicarbonate and 50 µM Na2S in the principal comparison. The retained supplement specifies 80% N2/20% CO2 and pH 7 adjusted before inoculation; the accepted main text instead gives 80% N2/15% CO2, an unresolved source discrepancy. Initial enrichments used DCMU and ascorbate, but the studied later MFGL cultures lacked added DCMU, ascorbate and sulfate, with reported residual sulfate below 0.9 µM. Inocula were washed three times with anoxic water. The culture was a consortium with Chlorobium-affiliated sequences and other anaerobic bacteria, not a pure Chlorobium strain. At least triplicate experiments were reported. Dark, no-added-Mn and uninoculated Mn-amended controls were included. These conditions are synthetic laboratory media, not industrial recovery or direct proof of ancient-ocean conditions.
Curated Evidence Points:
Section 1 defines the 1 mM Mn, illuminated two-week treatment and controls. Figures DR2-DR3 show its diffraction pattern with a dolomite standard and labeled 015/021 features; Table DR1 fits ordered dolomite phases in that arm. Figure DR4A-C shows mineral-encrusted Chlorobium-like cells in this same treatment, and Figure DR5 shows grains associated with EPS. The accepted claim is the source-assigned dolomite phase and culture association. EDS alone does not establish crystal ordering, and fitted phase percentages are not magnesium recovery yields, purified-product fractions or independent biological replicates.
Methods/Results report no detectable precipitates in uninoculated controls after two weeks, while Discussion explicitly says the product was not perfectly ordered. This supports a contribution of the inoculated biofilm under the reported conditions; it does not prove a specific gene, enzyme or organism is solely responsible. The 8-page accepted manuscript contains text and captions but no embedded main Figures 1-2; detailed main-figure measurements and an exact 0.1 mM dose response are not imported. The independently inspected original supplement provides the phase/condition evidence used here.
Control labels and some captions are inconsistent. Figure DR2 calls its dark trace Mn-amended whereas Table DR1 labels a dark row no Mn. DR7B identifies EPS-associated calcite in a dark/no-Mn arm, contrary to the accepted main text's broad no-minerals statement; DR8 only shows absence of cell-surface encrustation. DR4D/E are dark controls in the supplement but the main text refers to them as no-Mn light controls. DR3B is labeled 021 in the graphic and 012 in the caption; DR2's caption elsewhere lists 112. These discrepancies prevent a definitive phase-by-arm quantitative comparison and are not silently corrected. The illuminated 1 mM-Mn arm remains explicitly and consistently identified. Raw patterns, refinement uncertainty and complete sterile-control traces were not supplied in the inspected artifacts; ordering is retained as the authors' qualified assignment, not a new crystallographic reanalysis.

Sources & References

  1. ima_202609: IMA-CNMNC master list, September 2026: definitions pp. 1-2 and Dolomite row p. 58
    https://cnmnc.units.it/files/editor/IMA_Master_List_(2026-09).pdf (accessed 2026-10-14)
  2. handbook_dolomite: Handbook of Mineralogy: Dolomite, CaMg(CO3)2; mineral identity and occurrence, version 1
    https://www.handbookofmineralogy.org/pdfs/dolomite.pdf (accessed 2026-10-14)
  3. daye_2019: Daye, Higgins and Bosak (2019), Formation of ordered dolomite in anaerobic photosynthetic biofilms, Geology 47:509-512; author accepted manuscript Methods, Results and Discussion
    https://doi.org/10.1130/G45821.1 (accessed 2026-10-14)
  4. daye_accepted: MIT repository author accepted manuscript of Daye et al. 2019; text and figure captions, without embedded main Figures 1-2
    https://hdl.handle.net/1721.1/126802 (accessed 2026-10-14)
  5. daye_supplement: Daye et al. 2019, GSA Data Repository 2019187; complete official supplement, Sections 1-6, Figures DR2-DR10 and Table DR1
    https://doi.org/10.1130/2019187 (accessed 2026-10-14)

Curation History

Timestamp Curator Action Summary
2026-10-14T08:18:00.832546+00:00 codex (GPT-6; codex) CREATE Created distinct mineral identity and bounded primary microbial association or precipitation evidence; retained control, phase-assignment and source-access limitations.

Record source: data/records/dolomite.yaml