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Sauconite mineral

Sauconite is a Zn-rich smectite-group mineral with grandfathered status G and original-description year 1875 in the September 2026 IMA list, whose formula is Na0.3Zn3(Si,Al)4O10(OH)2·4H2O. The experimental material below is a synthetic Zn-rich trioctahedral smectite assigned to sauconite by combined diffraction and chemical characterization. It is distinct from generic saponite, zinc as an element, and mixed higher-temperature products. No constituent criticality designation is inherited.

Microbial & Biochemical Mechanisms (1)

Abiotic hydrothermal formation of source-assigned sauconite from a Zn-Al-Si gel

other

Hydrothermal treatment of a homogeneous Zn-Al-Si gel produced a Zn-rich expandable trioctahedral smectite assigned to sauconite. At 100 degrees C the reported XRD patterns contained no detected crystalline impurity phases; higher-temperature treatments also produced hemimorphite and, in the 200-degree seven-day product, willemite. This is an abiotic phase-formation experiment, not microbial extraction or recovery from waste.

Experimental Context & Analytical Limits:
Experimental section, Table 1 and Figures 1-2: tetraethyl orthosilicate, zinc chloride and aluminium chloride supplied the gel; sodium hydroxide adjusted pH to 10, followed by washing, redispersion with further sodium hydroxide and overnight aging. A Teflon-lined steel vessel operated at autogenous pressure. Table 1 reports 100 and 150 degrees C at 1, 3, 7 and 14 days, and 200 degrees C at 1, 3 and 7 days. Washed products were freeze-dried for more than two days before analysis. No microorganisms, natural ore feed or spent-material feed were used.
Curated Evidence Points:
Table 1 and Figures 1-2 show sauconite without XRD-detected impurities for the reported 100-degree treatments, hemimorphite in the 150-degree series, and hemimorphite plus willemite after seven days at 200 degrees. No detection limit, refined phase fraction or complete conversion yield is provided; the reported single-phase assignment does not exclude undetected or amorphous components.
Figures 1-6 and Tables 2-3 support the assignment using ethylene-glycol expansion to about 17 angstrom, a 060 spacing of 1.53-1.54 angstrom, flaky/turbostratic texture, FTIR and XPS. The S10 analytical sample is the 100-degree, 14-day product. Elemental composition and Zn coordination support a Zn-rich smectite, not an independently measured zinc-recovery efficiency.
Discussion attributes excess Zn and Na relative to ideal composition partly to interlayer or surface adsorption; not all Zn is demonstrated to occupy structural sites. The printed doubled ideal formula has an inconsistent hydroxyl normalization, so the authority formula is used for identity. Comparison with an earlier different-gel synthesis that produced little or no sauconite at 100 degrees makes the successful temperature recipe-specific. No catalytic-performance measurement, waste-recovery mass balance, microbial necessity or industrial deployment is demonstrated.

Sources & References

  1. ima_2026_09: IMA-CNMNC. The New IMA List of Minerals, September 2026, Sauconite row, PDF p193. Retained original re-inspected on the access date.
    https://cnmnc.units.it/files/editor/IMA_Master_List_(2026-09).pdf (accessed 2026-10-14)
  2. handbook_sauconite: Handbook of Mineralogy. Sauconite, version 1 (2001). Complete one-page identity and smectite-group membership.
    https://handbookofmineralogy.org/pdfs/sauconite.pdf (accessed 2026-10-14)
  3. yokoyama_2006: Yokoyama, Tamura, Hatta, Nemoto, Watanabe and Yamada. Synthesis and characterization of Zn-substituted saponite (sauconite). Clay Science 13(3):75-80, issue labelled 2006. Complete six-page J-STAGE original, Figures 1-6 and Tables 1-3. The original prints acceptance on 6 April 2007, later than its issue year; J-STAGE online availability is 20 September 2011.
    https://doi.org/10.11362/jcssjclayscience1960.13.75 (accessed 2026-10-14)

Curation History

Timestamp Curator Action Summary
2026-10-14T18:55:06.653612Z codex (GPT-6; codex) CREATE Created evidence-backed mineral identity with complete primary characterization, explicit experimental phase and control limits, and no inherited criticality or deployment claim.

Record source: data/records/sauconite.yaml