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Brucite mineral

Brucite is the magnesium hydroxide mineral Mg(OH)2. The IMA-CNMNC September 2026 master list gives grandfathered status G and the original-description year 1818, not a numbered approval identifier. It is distinct from elemental magnesium, magnesium-metal commodity, the brucite mineral group, and chemically unspecified magnesium hydroxide products. Field observations at Prony Bay document brucite encrusting microbial filaments; they do not establish that microbes are required for brucite formation. No criticality designation is inherited from magnesium.

Microbial & Biochemical Mechanisms (1)

Field-associated brucite encrustation of microbial filaments

biomineralization Microbial

At the Prony Bay hydrothermal field, brucite-rich mineral crusts occur around carbon-rich microbial filaments in young chimney conduits. Laser-microdissected mineralized filaments from ST09 gave XRD patterns assigned predominantly to brucite with minor hydrotalcite; microscopy and DNA staining support microbial sheaths within these structures. Filaments are proposed to provide nucleation surfaces during chimney consolidation. This is an observational organomineralization interpretation, not a controlled demonstration of microbial necessity or a quantified recovery process.

Experimental Context & Analytical Limits:
Natural hydrothermal chimneys sampled during the 2011 HYDROPRONY cruise, New Caledonia; ST09 is a juvenile active edifice at about 50 m water depth, compared with more mature ST07 and other sites. Reduced alkaline fluids derived from serpentinization mix with seawater. This is field occurrence studied by laboratory microscopy and diffraction, without a defined culture temperature, exposure duration, loading, inoculated isolate or industrial operation. SEM fragments were stored at 4°C; molecular/imaging fractions used preservation protocols rather than living precipitation assays. Filament-rich ST09 material yielded predominantly one uncultivated Firmicutes-affiliated 16S OTU; the nearest cultivated relative was only 88% similar, so no named species or metabolic pathway is assigned. Sequence abundance in mixed material does not prove that a single taxon precipitated the mineral. The source also recognizes abiotic precipitation from supersaturated alkaline fluids. No matched sterile, killed-biomass or pH-controlled formation experiment is provided.
Curated Evidence Points:
Methods p. 5 describes laser microdissection and XRD of individual encrusted ST09 filaments. Figures 2 and 3 show mineral-covered carbon-rich filaments, Mg/O-rich crusts and a brucite-dominated diffraction pattern; Figure 5 shows DNA-stained cells in microbial sheaths. These observations support brucite-associated microbial encrustation, not an independently resolved rate or mass yield. Minor hydrotalcite is a co-occurring phase of unresolved origin, not assumed to be microbial brucite conversion.
Discussion p. 11 explicitly states that thermodynamic supersaturation permits abiotic brucite precipitation and that high fluid pH already supplies the alkaline conditions. Sheaths as nucleation sites are proposed; functional groups, metabolic alkalinization and phase-specific causation are not experimentally isolated. Table 1 and pp. 11-14 describe mixed-sample sequence affiliation, not cultured strain verification; the paper itself warns that metabolisms cannot reliably be inferred from these distant relatives. The micrographs are spatial observations, not time-lapse proof of the depicted growth sequence. No magnesium extraction, isolated-product recovery or engineered deployment follows.

Sources & References

  1. ima_202609: IMA-CNMNC master list, September 2026: definitions pp. 1-2 and Brucite row p. 31
    https://cnmnc.units.it/files/editor/IMA_Master_List_(2026-09).pdf (accessed 2026-10-14)
  2. handbook_brucite: Handbook of Mineralogy: Brucite, Mg(OH)2; mineral identity and occurrence, version 1
    https://www.handbookofmineralogy.org/pdfs/brucite.pdf (accessed 2026-10-14)
  3. pisapia_2017: Pisapia et al. (2017), Mineralizing Filamentous Bacteria from the Prony Bay Hydrothermal Field Give New Insights into the Functioning of Serpentinization-Based Subseafloor Ecosystems; Methods and Results pp. 3-14, Figures 2-5 and Table 1
    https://doi.org/10.3389/fmicb.2017.00057 (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/brucite.yaml