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Nesquehonite mineral

Nesquehonite is the hydrated magnesium carbonate mineral species Mg(CO3)(H2O)2·H2O, listed as grandfathered in the September 2026 IMA-CNMNC list with original-description year 1890. That year is not an approval identifier. It is distinct from dypingite, hydromagnesite, elemental magnesium and the magnesite commodity. The evidence below concerns nesquehonite within laboratory precipitates, not magnesium metal or an industrially recovered product; no constituent criticality is inherited.

Microbial & Biochemical Mechanisms (1)

Nesquehonite associated with a Desemzia-affiliated solid culture

biomineralization Microbial

Associated Organisms: Desemzia incerta (NCBITaxon:82801)

Nesquehonite was identified by XRD among mixed mineral precipitates recovered from solid cultures of the Las Eras isolate LE1, affiliated by partial 16S sequence to Desemzia incerta. It was not detected in the study's liquid-culture assemblage. This supports occurrence in the tested microbial system; the missing reported control outcomes prevent concluding microbial necessity or a measured enhancement.

Experimental Context & Analytical Limits:
LE1 was isolated from the uppermost microbial mat at Las Eras, Spain. The paper reports 794-802-base partial 16S sequences and 99.8% similarity to the Desemzia incerta reference Y17300, which ENA identifies as DSM 20581. LE1 is not asserted to be DSM 20581, and the species CURIE expresses the reported affiliation only. LE-1 medium contained 1% yeast extract, 0.5% proteose peptone, 0.1% glucose and 2% NaCl (weight/volume), calcium and magnesium acetates at stated molar Mg/Ca 11, and 20 g/L Bacto-Agar for solid medium. Initial pH was 7.0, adjusted with 0.1 M KOH; medium was autoclaved at 121 degrees C for 20 minutes. Isolation plates were incubated aerobically; culture Results report mineral precipitation after 15 days at 30 degrees C in solid and liquid experiments. Vessel geometry, culture replication and a complete harvest-time series are not specified.
Curated Evidence Points:
Culture Results, Table 3 and Figure 5B identify nesquehonite in the solid-culture mixture, with several diffraction peaks labeled Nes. The liquid pattern in Figure 5A and its Table 3 row lack nesquehonite; huntite instead appears in the liquid arm. Hydromagnesite and dypingite are grouped as Hmg and are not reinterpreted as nesquehonite. The accepted outcome is a qualitative phase assignment, not a pure-phase yield.
Methods say uninoculated medium and medium with autoclaved cells were included in all experiments, but their mineral outcomes and matched diffraction traces are not reported in the inspected article. Thus control existence is not a demonstrated negative-control result. Table 3 is described as average semiquantitative analysis but its liquid and solid rows sum to 116 and 133.5 respectively; the nesquehonite cell 35 is not accepted as a normalized mass percentage or recovery yield. The text says Mg-calcite occurs only in solid culture, whereas the liquid Table 3 row includes it. No silent normalization or correction is applied.
Figures 6-7 predominantly characterize Hmg and other associated phases, not a nesquehonite-specific cell-surface nucleation sequence. Proposed EPS binding, biomass decay, alkalinity changes and Mg dehydration are interpretations, not directly demonstrated molecular steps for nesquehonite. Modeled initial bulk undersaturation is not a cell-scale saturation measurement. Field mat-water-interface occurrences and isotope mixtures are distinct from this culture assay and do not prove LE1 causes all natural nesquehonite. The source's stated nesquehonite H2O/Mg ratio of 2 conflicts with the total three waters in its formula and the current IMA formula; that ratio is not adopted. The modeled culture row in Table 1 uses pH 8.2, whereas the preparation method specifies initial pH 7.0; these are not silently treated as the same measured starting state.
In a different six-week laboratory experiment using filtered Atlin wetland water at room temperature with sunlight, the abiotic wetland-water control formed nesquehonite, whereas cyanobacterial enrichment biofilms formed dypingite and had no detected nesquehonite (Section 4.3, Figure 5C and Table 2). Nutrient additions were not shown to be matched, and the organisms and water chemistry differ from LE1. This counterexample limits any claim that nesquehonite requires microbes or universally increases in their presence; it does not refute the narrower LE1 culture-associated phase observation.

Sources & References

  1. ima_2026_09: IMA-CNMNC. The New IMA List of Minerals, September 2026. Pages 1-2 definitions and terms; hydromagnesite page 98, huntite page 97, nesquehonite page 154. Grandfathered description years are not approval identifiers.
    https://cnmnc.units.it/files/editor/IMA_Master_List_(2026-09).pdf (accessed 2026-10-14)
  2. sanz_montero_2019: Sanz-Montero, Cabestrero and Sánchez-Román (2019). Microbial Mg-rich Carbonates in an Extreme Alkaline Lake (Las Eras, Central Spain). Frontiers in Microbiology 10:148. DOI 10.3389/fmicb.2019.00148. Culture Medium and Microorganisms methods, culture Results, Table 3, Figure 5 and Discussion.
    https://doi.org/10.3389/fmicb.2019.00148 (accessed 2026-10-14)
  3. ncbi_desemzia: NCBI Taxonomy 82801: Desemzia incerta, species rank. This species identifier does not identify experimental isolate LE1.
    https://www.ncbi.nlm.nih.gov/taxonomy/82801 (accessed 2026-10-14)
  4. ena_y17300: ENA accession Y17300.1, Desemzia incerta 16S rRNA gene, strain DSM 20581. The 2019 study cites this as its closest-relative reference sequence, not a deposited LE1 sequence.
    https://www.ebi.ac.uk/ena/browser/view/Y17300.1 (accessed 2026-10-14)
  5. power_2007: Power et al. (2007). Biologically induced mineralization of dypingite by cyanobacteria from an alkaline wetland near Atlin, British Columbia, Canada. Geochemical Transactions 8:13. DOI 10.1186/1467-4866-8-13. Sections 3.2-3.5 and 4.3, Figure 5C and Table 2 for the distinct laboratory wetland-water comparison.
    https://doi.org/10.1186/1467-4866-8-13 (accessed 2026-10-14)

Curation History

Timestamp Curator Action Summary
2026-10-14T07:24:42.406309+00:00 codex (GPT-6; codex) CREATE Created nesquehonite mineral identity and bounded LE1 culture-associated XRD evidence, distinguishing reference taxonomy, missing control results, non-normalized phase cells and the contrasting Atlin experiment.

Record source: data/records/nesquehonite.yaml