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Nobleite mineral

Nobleite is the CaB6O9(OH)2(H2O)3 mineral species in the September 2026 IMA-CNMNC list, with approved status A and special-procedure notation 1967 s.p.; this notation is not a unique approval identifier. It is distinct from gowerite, elemental boron and the borates commodity. Erd, McAllister and Vlisidis characterized natural nobleite from the Death Valley region, California, and compared its diffraction pattern with a separately synthesized product. Their older oxide formula CaO·3B2O3·4H2O has the same elemental stoichiometry as the current IMA formula. Natural single-crystal data in Table 1 give monoclinic P21/a symmetry, with P21/n as an alternative setting. This record does not infer criticality, microbial formation or commercial recovery from mineral identity.

Microbial & Biochemical Mechanisms (1)

Laboratory precipitation of synthetic nobleite

other

Calcium oxide, boric acid and water yielded fine-grained synthetic nobleite in a controlled laboratory preparation. Phase identification rests on comparison with the natural mineral's powder diffraction pattern. The experiment establishes formation of the solid phase, not a boron recovery efficiency or a demonstrated molecular nucleation pathway.

Experimental Context & Analytical Limits:
Erd et al. mixed 1.6 g CaO, 10.0 g H3BO3 and 25 mL water, stirred for 30 hours at 48 degrees C, then held the product at 68 degrees C for ten days. The material was filtered, washed successively with distilled water, methyl alcohol and acetone, and air-dried at room temperature. The reported recipe gives no pH, isolated yield, quantitative phase purity, replicate count or solution mass balance. No organisms or industrial feed were used.
Curated Evidence Points:
Support Source: erd1961
The synthesis paragraph on p. 569 reports crystals up to four micrometres in diameter and gives the preparation above. The actual natural-versus-synthetic powder data are in Table 2, pp. 565-567, although the synthesis paragraph incorrectly points to Table 1. Table 2 identifies its synthetic column as material prepared by R. C. Erd. Its footnote warns that natural preferred orientation and different radiation conditions prevent direct comparison of the reported diffraction intensities.
Context_only Source: erd1961
Table 3 chemistry comes from a separate 0.500 g handpicked natural-crystal sample, not the precipitation product. The natural occurrence and weathering interpretation are not a controlled transformation of a named parent mineral. Page 570 states that the authors' then-available results do not indicate a simple hydration-dehydration relationship between nobleite and gowerite. The older equilibrium solubility values quoted from Nikolaev and Chelishcheva (1940) are secondary evidence here and are not adopted as measurements of this synthesis.

Sources & References

  1. ima_2026_09: IMA-CNMNC, The New IMA List of Minerals, September 2026: PDF page 156, Nobleite row; page 1, status/year definitions. Fresh official list and current-list landing page checked on 16 October 2026.
    https://cnmnc.units.it/files/editor/IMA_Master_List_(2026-09).pdf (accessed 2026-10-16)
  2. erd1961: Erd, McAllister and Vlisidis (1961), Nobleite, another new hydrous calcium borate from the Death Valley region, California, American Mineralogist 46, 560-571. Complete society-hosted original: natural occurrence pp. 560-563; Table 1 p. 564, crystallography; Table 2 pp. 565-567, natural/synthetic diffraction; Table 3 p. 569, natural chemistry; own synthesis p. 569; species relationship p. 570.
    https://msaweb.org/AmMin/AM46/AM46_560.pdf (accessed 2026-10-16)

Curation History

Timestamp Curator Action Summary
2026-10-16T03:44:34.595995Z codex (GPT-6; codex) CREATE Created a distinct nobleite species record with the original laboratory precipitation recipe and diffraction evidence, separating natural chemistry, secondary solubility reports and unsupported nobleite-gowerite interconversion.

Record source: data/records/nobleite.yaml