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Triphylite mineral

Triphylite is the lithium iron(II) phosphate mineral LiFe2+(PO4), listed by IMA-CNMNC in September 2026 as grandfathered, with original-description year 1834 rather than an approval identifier. It is distinct from Mn2+-dominant lithiophilite and oxidized, lithium-deficient members of the group. Losey2004 characterized natural pegmatite crystals by electron microprobe and single-crystal diffraction in the Pbnm setting of orthorhombic space group 62; Pmnb in the Handbook is another setting. The natural samples are solid solutions, including Mg substitution, not all pure LiFePO4. Lithium was not independently measured in that study: Li2O was assumed for matrix correction and Li-site occupancy fixed during refinement. The accepted transformation study uses a separately characterized natural triphylite specimen with minor sarcopsides visible microscopically, and demonstrates abiotic oxidation with spatially resolved lithium depletion, not microbial weathering or a recovered lithium product. The historical ferrisicklerite product name in the 2013 original is discredited under the 2022-approved nomenclature published in 2023; that publication classifies the studied Tri-77 and Tri-87 products as heterosite. No constituent-element criticality designation is inherited.

Microbial & Biochemical Mechanisms (1)

Hydrothermal oxidation with local lithium depletion

redox transformation

Oxidizing acid treatment produced an iron-oxidized, lithium-depleted reaction region in natural triphylite while retaining an unreacted core in the cuboid experiment. Separate powder experiments support oxidation and structural change. Crystallographic and microscopic observations support a topotactic relationship, but do not establish a unique atomistic pathway, a closed lithium balance or an isolated recovery yield. This experiment is also the source of the synthetic-lithiophilite null arm curated in cmmmech:lithiophilite; the two material records do not represent independent replications.

Experimental Context & Analytical Limits:
Schmid-Beurmann2013 used Palermo Mine, New Hampshire specimen 9706.41, either powdered to 125-250 micrometres or cut into polished cuboids with 2.5-mm edges. Closed 3-cm3 Teflon-lined vessels contained 1 mL of 0.1 N HCl, without oxygen buffering, under internally generated pressure. Table 1 assigns Tri-87 to a 53.5-mg cuboid with 21 mg KMnO4 at 120 degrees C for 8 days; the separate Tri-77 powder run used 50.8 mg solid and 20.2 mg KMnO4 at 120 degrees C for 8 days. Solids were separated, water-washed and dried at 50 degrees C. No biological component, matched acid-only/no-oxidant control, independent replicate count or aqueous lithium mass balance is reported. These are laboratory reactions, not an industrial extraction demonstration.
Curated Evidence Points:
Methods pages 502-505, Tables 2-3 and 7-8, and Results pages 508-511 characterize the natural starting material and the separate Tri-77 product using diffraction, microprobe, SIMS and iron Mossbauer spectroscopy. Minor sarcopsides were visible in the natural crystal by microscopy although powder diffraction showed no significant secondary phase. Tri-77 had approximately 93% of its iron in the ferric state. Its diffuse X-ray background between about 20 and 30 degrees 2-theta indicates an amorphous contribution, so the source-assigned crystalline product is not an established phase-pure recovered mass.
Table 1 (page 503), Tables 8-9 (pages 509-510), Figures 3-5 (pages 511-512) and Results page 511 resolve Tri-87 into an outer opaque Mn-rich layer about 20 micrometres thick, a red-brown reaction rim about 50-100 micrometres thick, and an unreacted triphylite core. Three EPMA/SIMS profiles cross the interface; measured lithium changes from approximately one atom per formula unit in the core to 0.30(7) in the rim. This is a local solid composition, not a percentage of total feed lithium extracted or recovered. The cuboid formula combines these profiles with valence information from the separate powder experiment; it is not a direct independent Mossbauer measurement of the cuboid rim.
Discussion pages 511-514 uses shared optical extinction, retained structural relationships and a porous reaction region to interpret topotactic oxidation and possible dissolution-reprecipitation. These observations do not uniquely prove one transport mechanism. Potassium enrichment could represent structural incorporation or a pore-hosted phase. Table 1 also shows temperature- and oxidant-dependent products; peroxide runs cannot be merged with the selected permanganate arms. The synthetic-lithiophilite Tri-74 comparison differs in oxidant dose, duration, grain size and natural versus synthetic provenance, despite the Results phrase describing the same conditions.
Context_only Source: lyalina2023
Tables 2-3, Algorithm 1 and sections 4-6, pages 432-435, retain triphylite and lithiophilite as distinct species but discredit ferrisicklerite and sicklerite. Table 3 explicitly assigns the recalculated 2013 Tri-77 and Tri-87 samples to heterosite. This is a nomenclatural reassessment of the same experimental lineage, not new transformation evidence. Classification requires valence-resolved chemistry and site occupancy; color or total Fe/Mn ratio alone is insufficient for oxidized compositions. The supplement's recalculated Tri-77 Li2O weight percentage is not used as an extraction measurement.

Sources & References

  1. ima_2026_09: IMA-CNMNC. The New IMA List of Minerals, September 2026. PDF page 220, Triphylite row LiFe2+(PO4), G, 1834; page 1 defines grandfathered status and original-description year.
    https://cnmnc.units.it/files/editor/IMA_Master_List_(2026-09).pdf (accessed 2026-10-15)
  2. handbook_triphylite: Handbook of Mineralogy. Triphylite, Li(Fe2+,Mn2+)PO4. Complete one-page identity, orthorhombic Pmnb structure, chemistry and natural occurrence entry.
    https://www.handbookofmineralogy.org/pdfs/triphylite.pdf (accessed 2026-10-15)
  3. losey2004: Losey A, Rakovan J, Hughes JM, Francis CA, Dyar MD (2004). Structural variation in the lithiophilite-triphylite series and other olivine-group structures. Canadian Mineralogist 42:1105-1115. Complete eleven-page original, Tables 1-5 and Figures 1-7; underlying CISTI-deposited structure factors and anisotropic parameters were not acquired.
    https://doi.org/10.2113/gscanmin.42.4.1105 (accessed 2026-10-15)
  4. schmid_beurmann2013: Schmid-Beurmann P, Ottolini L, Hatert F, Geisler T, Huyskens M, Kahlenberg V (2013; online 2012). Topotactic formation of ferrisicklerite from natural triphylite under hydrothermal conditions. Mineralogy and Petrology 107:501-515. Complete fifteen-page original, Tables 1-9 and Figures 1-5. Historical product nomenclature is qualified using Lyalina2023.
    https://doi.org/10.1007/s00710-012-0250-6 (accessed 2026-10-15)
  5. lyalina2023: Lyalina LM, Selivanova EA, Hatert F (2023). Nomenclature of the triphylite group of minerals. European Journal of Mineralogy 35:427-437. Complete original, Tables 1-3, Figures 1-5 and Algorithm 1; official supplement title page and native Supplement.xlsx inspected. The October 2022 CNMNC-approved scheme discredits ferrisicklerite and sicklerite; Table 3 recalculates the same 2013 samples rather than reporting a new oxidation experiment.
    https://doi.org/10.5194/ejm-35-427-2023 (accessed 2026-10-15)

Curation History

Timestamp Curator Action Summary
2026-10-15T10:30:56.440916+00:00 codex (GPT-6; codex) CREATE Added current mineral identity and a narrowly scoped abiotic hydrothermal experiment, preserving natural-versus-synthetic provenance, conditional nulls, shared study lineage and updated nomenclature.

Record source: data/records/triphylite.yaml