CMMMech
CMMMech > Mineral > Larderellite

Larderellite mineral

Larderellite is the ammonium borate mineral (NH4)B5O7(OH)2·H2O in the September 2026 IMA-CNMNC list. Its grandfathered status G and year 1854 describe its nomenclatural history, not a sequential approval identifier. It is distinct from other ammonium borates, a generic experimental ammonium salt, elemental boron and the borates commodity. Fastelli and colleagues characterized natural material from Larderello, Italy, by powder diffraction, reflectance spectroscopy and thermal analysis. Figure 1b's starting-sample diffraction fit reports 94.3% larderellite, 0.4% bassanite and 5.3% polyhalite. These are fitted phase fractions in a mixed specimen, not an independent chemical-purity assay. The study does not establish biological origin or microbial activity merely because the mineral contains ammonium, and no criticality designation is inherited from boron.

Microbial & Biochemical Mechanisms (1)

Thermal mass loss in a natural larderellite-bearing sample

other

Laboratory heating produced multistep mass loss and endothermic thermal features. The authors interpret these as removal of water and ammonia, but the gas assignments and quantitative mass balance are not independently established by the reported methods. The supported observation is qualified bulk thermal decomposition of this mixed natural sample, not a verified pure-mineral gas yield or recovered boron product.

Experimental Context & Analytical Limits:
Thermogravimetry used approximately 20 mg on a Netzsch STA 490; separate differential scanning calorimetry used approximately 3 mg on a Mettler Toledo instrument. Both used a 10 degrees C per minute heating rate in air flowing at 50 mL per minute. Figure 2b plots the TG series to approximately 1023 K and the DSC series to approximately 773 K. These are separate laboratory aliquots and instruments; the methods report no coupled evolved-gas analysis or replicate uncertainty. Contributions from bassanite, polyhalite and adsorbed water cannot be isolated from the bulk curves. This experiment does not test microbial transformation, extraction, isolated-product recovery or industrial operation.
Curated Evidence Points:
Section 2.3 and Figure 2b document mass decrease with heating and accompanying endothermic features. Figure 1b establishes that the starting natural material includes two sulfate impurities. The observation supports a laboratory thermal transformation of the larderellite-bearing specimen while retaining its mixed-feed scope.
Section 3.1 states a total mass loss of about 32.5%, whereas Figure 2b visually ends at about 72-73% mass remaining. The plotted endpoint is an approximate visual reading, not a digitized raw datum, and the discrepancy remains unresolved. The prose calls the process six major steps but enumerates eight temperatures. Its partition into water and NH3 losses relies on thermal assignments without directly measured evolved-gas identities; those individual yields are not adopted. The preceding temperature/product sequence is attributed to Waclawska (1997), reference 58, whose full text was not acquired. It is not a new phase-product identification by the 2020 experiment. No claim of identified crystalline boron oxide or a closed boron mass balance is made here.

Sources & References

  1. ima_2026_09: IMA-CNMNC, The New IMA List of Minerals, September 2026: PDF page 121, Larderellite row; page 1, status and year definitions. Fresh official PDF and relevant rows checked on 16 October 2026.
    https://cnmnc.units.it/files/editor/IMA_Master_List_(2026-09).pdf (accessed 2026-10-16)
  2. fastelli2020: Fastelli M, Comodi P, Maturilli A and Zucchini A (2020), Reflectance Spectroscopy of Ammonium Salts: Implications for Planetary Surface Composition, Minerals 10, 902, DOI 10.3390/min10100902. Complete 22-page journal PDF, version 2 as identified by its update link, from the University of Perugia repository. Table 1, p. 4, sample origin; sections 2.2-2.3, pp. 4-5, methods; section 3.1 and Figures 1b-2b, pp. 7-8, mixed-sample diffraction and thermal results.
    https://research.unipg.it/retrieve/e3aa200f-fb2b-ebae-e053-6605fe0a5b79/minerals-10-00902-v2.pdf (accessed 2026-10-16)

Curation History

Timestamp Curator Action Summary
2026-10-16T01:32:12Z codex (GPT-6; codex) CREATE Created a distinct larderellite species record with qualified mixed-sample thermal evidence, retaining inconsistent total loss, step counting and unverified gas/product assignments.

Record source: data/records/larderellite.yaml