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Ezcurrite mineral

Ezcurrite is the grandfathered sodium-borate mineral Na2B5O7(OH)3·2H2O in the September 2026 IMA-CNMNC list. The list's 1957 entry is the original-description year, not an IMA approval number. Hurlbut and Aristarain's 1967 restudy characterized natural crystals from Tincalayu, Argentina, embedded in borax; possible rivadavite inclusions were invoked to explain the departure of the wet analysis from ideal composition. Cannillo, Dal Negro and Ungaretti's 1973 study established a triclinic P-1 structure containing pentaborate units linked into chains along c, with two tetrahedral and three trigonal boron sites per unit. That study did not repeat the chemical analysis or unit-cell determination for its fragment. Only five of seven hydrogen positions were located; one hydrogen from each water molecule remained unresolved. The 1967 proposed hydroxyl/water partition was superseded by this structural model. The historical comparison with Suhr's synthetic borate does not make nasinite or associated kernite interchangeable with ezcurrite. This mineral species is distinct from elemental boron and the borates commodity; criticality, microbial activity and industrial recovery are not inferred.

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Microbial & Biochemical Mechanisms (2)

Ezcurrite other Laboratory thermal alteration of natur other Reported laboratory crystallization of

Laboratory thermal alteration of natural ezcurrite

other

Heating the natural mineral produced an amorphous material, subsequent crystallization and melting. Quenching the melt produced glass, whereas slow cooling produced a crystalline material with optical and diffraction properties different from the material crystallized during heating. Water-loss assignments are interpretations of thermal events rather than direct evolved-gas measurements or boron recovery yields.

Experimental Context & Analytical Limits:
The 1967 study used natural Tincalayu material. Figure 6 specifies differential thermal analysis at 20 degrees C per minute, a Pt/Pt-13%Rh thermocouple, a zero-degree reference junction and Al2O3 reference material. Atmosphere, sample mass, quantified thermal-aliquot purity and replicate count are not stated. The possible inclusions discussed for the chemical analysis are not assigned a quantified fraction in the thermal aliquot. Kernite is a separate comparison specimen. Quench and slow-cooling rates are unspecified. No microorganisms, pilot operation or isolated boron product were tested.
Curated Evidence Points:
Pages 1056-1057 and Figure 6 report an endotherm at 280 degrees C followed by amorphization, an exotherm at 680 degrees C accompanied by a crystalline phase, and a melting endotherm at 780 degrees C. The authors provided optical observations and selected powder spacings for the heating product and a different slow-cooled product; quenching gave glass. These are specimen- and heating-program-specific observations, not equilibrium phase boundaries or measured fractions of transformed mineral.
The 280-degree event was interpreted as structural water loss; the broader approximately 575-degree event may represent OH loss. The abstract states the latter assignment more strongly than the results text. Neither evolved gases nor quantitative product compositions were measured in this account, and neither heated crystalline product is adopted here as a chemically identified recovered compound.

Reported laboratory crystallization of synthetic ezcurrite

other

The 1967 authors reported successful laboratory preparation of the synthetic counterpart of ezcurrite by concentrating borax-boric-acid solutions, with a qualitatively better crop in a separate NaCl-saturated trial. The account supports reported crystallization, without a quantified product yield, purity comparison or extraction from natural ore.

Experimental Context & Analytical Limits:
Page 1058 describes two trials adapted from Suhr's earlier patent. The first used 10 g borax, 2.16 g boric acid and 10 g water, boiled until crystallization was nearly complete, then diluted with 10 mL cold water before filtration. The second saturated the above solution with NaCl and concentrated it above 51 degrees C. The specific borax reagent hydration/purity, NaCl amount, residence times, replicates, product masses and trial-specific characterization data are not supplied. These trials are distinct from the natural-crystal thermal experiment and from inferred geological formation.
Curated Evidence Points:
The Synthesis section on p. 1058 explicitly states that two methods were tested with good results and describes the preparation and filtration steps. It reports a better crop for the NaCl-saturated method without numerical comparison. This supports the authors' qualitative synthesis observation, not a measured recovery percentage or independent proof of phase purity for each trial.

Sources & References

  1. ima_2026_09: IMA-CNMNC, The New IMA List of Minerals, September 2026, PDF page 66, Ezcurrite row: Na2B5O7(OH)3·2H2O, status G, original-description year 1957; page 1, field definitions. Current official landing page and dated PDF checked 16 October 2026.
    https://cnmnc.units.it/files/editor/IMA_Master_List_(2026-09).pdf (accessed 2026-10-16)
  2. hurlbut_aristarain1967: Hurlbut and Aristarain (1967), Ezcurrite, 2Na2O·5B2O3·7H2O: A restudy, American Mineralogist 52, 1048-1059. Complete twelve-page original inspected: occurrence pp. 1048-1049; diffraction Table 4 p. 1054; chemistry Tables 5-6 p. 1055 and interpretation p. 1056; thermal observations pp. 1056-1057, Figure 6 p. 1057; separate synthesis trials p. 1058. The text's reference to Ito's analysis as Table 5 column 3 conflicts with the table's column 1 label and Table 6; no historical assay column is silently substituted for the present study.
    https://msaweb.org/AmMin/AM52/AM52_1048.pdf (accessed 2026-10-16)
  3. cannillo1973: Cannillo, Dal Negro and Ungaretti (1973), The crystal structure of ezcurrite, American Mineralogist 58, 110-115. Complete six-page original inspected: specimen and methods p. 110; atomic parameters Table 1 and Figures 1-2 p. 111; geometry Tables 3-6 pp. 112-113; Figures 3-4 p. 113; hydrogen and displacement discussion, Tables 7-8 p. 114. The reported R=0.050 applies to observed reflections; 893 of 1974 collected independent reflections were classed as unobserved. External structure-factor Table 2, NAPS 01978, was not acquired or independently re-refined.
    https://msaweb.org/AmMin/AM58/AM58_110.pdf (accessed 2026-10-16)

Curation History

Timestamp Curator Action Summary
2026-10-16T09:20:43Z codex create Created an evidence-backed ezcurrite species record from current IMA identity and complete 1967/1973 originals, preserving thermal, synthesis, chemistry and hydrogen-model limits; no criticality or microbial claim inferred.

Record source: data/records/ezcurrite.yaml