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Gowerite mineral

Gowerite is the Ca(H2O)[B5O8(OH)][B(OH)3]·2H2O mineral species in the September 2026 IMA-CNMNC list, with approved status A and special-procedure notation 1962 s.p.; the notation is not a unique approval identifier. The older CaO·3B2O3·5H2O and Ca[B5O8(OH)][B(OH)3]·3H2O formulas have the same elemental stoichiometry. Natural Furnace Creek crystals and separately synthesized crystals have been studied by diffraction. The monoclinic P21/a structure contains borate sheets, isolated B(OH)3 groups and three water molecules per formula unit, including one calcium-coordinated water molecule. The 1972 natural-crystal study did not locate hydrogen atoms; the 2025 synthetic-crystal study refined hydrogen positions using distance constraints. Gowerite is distinct from nobleite, elemental boron and the borates commodity. No criticality or microbial mechanism is inferred from its boron content.

Microbial & Biochemical Mechanisms (2)

Laboratory precipitation from calcium acetate and boric acid

other

Erd et al. obtained a fine precipitate identified as gowerite by comparison with the natural mineral's powder diffraction. A separate unstirred preparation reportedly produced larger crystals, but a later study failed to replicate that room- temperature single-crystal route. The disagreement limits generalization of the older preparation.

Experimental Context & Analytical Limits:
The 1959 stirred experiment combined 20 g calcium acetate monohydrate, Ca(C2H3O2)2·H2O, 40 g boric acid and 100 mL water at 35 degrees C with continuous stirring for 24 hours. The reported initial and final pH were approximately five. A separate preparation of the same composition stood at room temperature for 18 days without stirring. These are distinct arms, not sequential steps. Neither experiment reports an isolated boron yield, quantitative phase purity, solution mass balance or replicate count.
Curated Evidence Points:
Support Source: erd1959
Pages 917-918 report the stirred recipe, describing its extremely fine precipitate as nearly pure synthetic gowerite. Table 1, p. 916, compares the natural and synthetic powder patterns; nearly pure is a qualitative description, not a measured purity fraction. Page 918 reports larger crystals after the separate 18-day unstirred preparation. These are the authors' own experiments, although their cited Gode (1949) precursor procedure was available to them only as an abstract.
Manuscript p. 14, lines 224-228, explicitly reports unsuccessful attempts to replicate the 1959 room- temperature, 18-day method for growing single crystals. It does not give the failed experiment's product identity, detailed deviations or replicate count, and does not specifically test the separate 35-degree, 24-hour stirred route. This null cannot establish that gowerite never forms under either historical set of conditions.

Laboratory hydrothermal formation of synthetic gowerite

other

A calcium chloride, boric acid and sodium hydroxide mixture produced gowerite in a hydrothermal synthesis originally intended to make ulexite. A selected crystal was structurally refined as gowerite. The observation supports solid-phase formation, not quantitative bulk purity, metal extraction efficiency or industrial recovery.

Experimental Context & Analytical Limits:
The 2025 manuscript used 1.00 g H3BO3, 0.476 g CaCl2·2H2O and 0.129 g NaOH with 10 mL Milli-Q water in a sealed 28 mL Teflon-lined stainless-steel autoclave. It was heated at 120 degrees C for 12 hours under autogenous pressure, then cooled to 30 degrees C at 0.2 degrees C per minute. The precipitate was collected through a 0.1-micrometre membrane, rinsed with Milli-Q water and air-dried overnight at 20 degrees C. Pressure and pH were not numerically reported. No biological agent or industrial feed was used.
Curated Evidence Points:
Manuscript pp. 6-9 give the synthesis and selected-crystal diffraction methods, and p. 14 reports gowerite formation. The selected crystal was approximately 0.10 x 0.05 x 0.05 mm. Figure 1 and Tables 1-3 show the refined solid structure and interpreted hydrogen bonding; this does not measure a solution nucleation sequence. The abstract reports P21/a, four formula units per cell and an R1 refinement index of 4.13% for 1730 observed reflections.
Page 7 reports bulk powder-pattern agreement with a gowerite reference, but its cited supplementary Figure S1 was not acquired. No quantitative phase fraction or isolated recovery yield is available. Pages 14-15 report priceite instead under hotter, longer or more alkaline conditions, including 150 degrees C for 48 hours and a separate 5:1:5 H3BO3:CaCl2·2H2O:NaOH molar mixture at 150 degrees C for 12 hours. These endpoint comparisons do not directly demonstrate the proposed intervening dissolution of gowerite or inheritance of intact borate units in solution. They are not treated as a complete temperature-time-pH phase diagram.
Context_only Source: konnert1972
The earlier structure used a natural Furnace Creek crystal, explicitly identified on p. 382, and provides a separate structural comparison. Its proposed hydrogen bonding and water-release order were not located hydrogen sites or an in-situ dehydration sequence. Page 390 warns that heated mass loss may include molecular B(OH)3; the 1959 and 2025 discussions of thermal behavior do not justify assigning all mass loss solely to water.

Sources & References

  1. ima_2026_09: IMA-CNMNC, The New IMA List of Minerals, September 2026: PDF page 85, Gowerite row; page 1, status/year definitions. Fresh official list checked on 16 October 2026. The current CNMNC landing page also explains the June 2025 distinction between coordinated and uncoordinated water notation.
    https://cnmnc.units.it/files/editor/IMA_Master_List_(2026-09).pdf (accessed 2026-10-16)
  2. erd1959: Erd, McAllister and Almond (1959), Gowerite, a new hydrous calcium borate, from the Death Valley region, California, American Mineralogist 44, 911-919. Complete society-hosted original: natural sample p. 914; powder data Table 1 p. 916; chemical methods p. 917 and Table 2 p. 919; own synthesis pp. 917-918; differential thermal observations p. 918.
    https://msaweb.org/AmMin/AM44/AM44_911.pdf (accessed 2026-10-16)
  3. konnert1972: Konnert, Clark and Christ (1972), Gowerite, CaB5O8(OH)·B(OH)3·3H2O: crystal structure and comparison with related borates, American Mineralogist 57, 381-396. Complete 16-page original: natural crystal and methods pp. 382-384; atomic parameters Table 1 p. 385; Figures 1-2 pp. 385-386; structure pp. 384-390. Separately deposited structure factors, NAPS 01708, were not acquired.
    https://msaweb.org/AmMin/AM57/AM57_381.pdf (accessed 2026-10-16)
  4. kyono2025: Kyono and Yamaguchi (2025), Gowerite, Ca[B5O8(OH)][B(OH)3]·3H2O: Revisiting the crystal structure and exploring its formation context, American Mineralogist 110, 306-311, DOI 10.2138/am-2024-9367. Inspected complete 33-page institutional accepted manuscript labelled Revision 1: synthesis pp. 6-7, diffraction/refinement pp. 7-9, formation results and failed replication pp. 14-15, Figures 1-2 pp. 28-29, Tables 1-3 pp. 30-33. Supplementary Figure S1, Tables S1-S2 and a machine-readable structure model were not acquired; the final publisher PDF was inaccessible.
    https://tsukuba.repo.nii.ac.jp/record/2014708/files/AM_110-306_AM.pdf (accessed 2026-10-16)

Curation History

Timestamp Curator Action Summary
2026-10-16T03:45:59.759341Z codex (GPT-6; codex) CREATE Created a distinct gowerite species record with separate historical and hydrothermal precipitation experiments, preserving the later failed single-crystal replication, supplementary-data access limits and untested molecular interpretations.

Record source: data/records/gowerite.yaml