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Molybdenite mineral

Molybdenite is the MoS2 mineral species, grandfathered in the September 2026 IMA list with original-description year 1796. It is distinct from elemental molybdenum, dissolved molybdate, manufactured MoS2 and mixed ores or concentrates. The experiment below concerns molybdenite within a heterogeneous commercial ore-grade specimen, not a purified mineral. No criticality designation is inherited from molybdenum.

Microbial & Biochemical Mechanisms (1)

Molybdenite persistence during culture-associated companion-sulfide leaching

bioleaching Microbial

Associated Organisms: Acidithiobacillus ferrooxidans (NCBITaxon:920)

In laboratory bioleaching assays with Acidithiobacillus ferrooxidans LR, molybdenite persisted in a mixed sulfide specimen while the authors interpreted changes in iron chemistry and residue XRD as preferential removal of companion pyrite and pyrrhotite. Molybdenum in sampled liquid remained below the reported detection limit in both inoculated and uninoculated conditions. This is a bounded attempted-leaching result and companion-phase observation, not demonstrated microbial molybdenite oxidation, molybdenum extraction or isolated-product recovery. The authors' proposed galvanic protection of molybdenite was not directly measured.

Experimental Context & Analytical Limits:
The natural ore-grade material came from Ward's Natural Science Establishment, Rochester, New York; the specimen's mine origin is not supplied. It was ground below 0.2 mm and contained 0.8 wt% Mo, 34.0 wt% Fe and 23.0 wt% S. Initial XRD identified molybdenite, pyrite and pyrrhotite, with additional unidentified copper-mineral peaks. LR was isolated from acidic uranium-ore leach liquor at Lagoa Real, Bahia, Brazil, and adapted to the mixed sulfide before inoculation. No authenticated strain accession is assigned. The 43-day flask study used 250 mL Erlenmeyers containing 150 mL culture medium and 2.5% w/v ore, autoclaved at 120 degrees C for 30 minutes, then inoculated at 5% v/v and shaken at 150 rpm and 30 plus or minus 2 degrees C. Inoculated arms with and without 30 mmol/L supplemental Fe(II) had corresponding uninoculated controls; an additional uninoculated Fe(III) control was included. The cited T-and-K medium recipe is not reproduced in full. Flask replication, inoculum cell density, washing status and initial pH are not explicitly given. All flasks required early acid corrections; exact acid doses and timing are unavailable. Separate triplicate resting-cell respirometry does not supply those missing flask details. These are laboratory observations, not an industrial process demonstration.
Curated Evidence Points:
Experimental methods on pages 1095-1096 and the liquid-phase results on page 1098 report Mo below 2 mg/L, the stated detection limit, in all assays. Mo was measured by inductively coupled plasma spectrometry in supernatant after centrifugation; the instrument subtype is not specified. This censored solution concentration is neither zero nor a recovered fraction of feed molybdenum. No complete molybdenum mass balance, isolated product yield or quantified concentrate upgrade is supplied.
Figures 5-6 identify the starting mixed phases and show residue patterns after 22 days. The authors assign disappearance of pyrite and pyrrhotite peaks in inoculated arms, while corresponding uninoculated residues retain pyrite peaks; molybdenite peaks remain. This is qualitative phase evidence for culture-associated companion-sulfide removal. It does not quantify absolute mineral consumption, demonstrate direct enzymatic attack or establish oxidation of the molybdenite fraction.
The solid-phase paragraph on page 1098 says that inoculated samples showed no mineralogical changes after the period just discussed. The temporal wording may mean no further changes after day 22, consistent with earlier companion-sulfide loss, rather than no change from the starting material. Its comparison baseline is not explicit, so a definite source contradiction is not inferred. Qualitative XRD does not establish absolute complete oxidation. The same page reports persistent molybdenite peaks through 43 days in both inoculated and uninoculated flasks, but explicitly labels the final inoculated patterns as data not shown.
Original Figure 2S shows molybdenite peaks in 43-day uninoculated residues without added iron, with Fe(II), and with Fe(III). It does not show the missing 43-day inoculated patterns. Figure 1S concerns oxygen-consumption kinetics of the heterogeneous specimen and cannot establish molybdenite oxidation independently of its iron sulfides.
Page 1097 and Figure 2 describe an early pH rise toward 4 and periodic acid corrections over approximately the first 15 days, followed by differing culture/control trajectories and eventual pH 1.7-1.9 after about day 25. The controls therefore do not isolate a pH-independent cell effect. Figure captions label the Fe(III) control as 30 mmol/L Fe(III), whereas the methods describe 30 mmol/L ferric sulfate, leaving the stated addition basis ambiguous. The result is confined to this heterogeneous feed and assay; it does not establish universal resistance of molybdenite to microbial or chemical leaching under other conditions.
A separate laboratory comparison in Sections 2.3 and 3.3 uses the Mo-adapted consortium WZ-Q, not LR, with a mineral-processed molybdenite concentrate containing reported Mo 12.40% and S 14.25% in Table 2. Its mine origin, processing route and complete phase composition are unspecified. The 30-day assay used 250 mL flasks, 10% w/v pulp, 10% v/v inoculum and 9K medium with nominal initial pH 1.4; samples from one flask were collected every five days for filtered-residue analysis. No matched uninoculated concentrate series or flask replication is reported. The temperature, agitation and working volume are not explicitly assigned to this assay; the adjacent black-shale conditions and triplication are not transferred. WZ-Q is an unresolved community, and no isolate or taxon identifier is inferred for it. This is not a replication of the 2007 mixed-specimen assay.
Figure 4b labels Mo and S as percentages in leaching residue, showing a small Mo-content decline and a larger S-content decline. Section 3.3 instead describes monitoring aqueous concentrations, leaving the fraction assignment inconsistent. Section 2.4 reports residue digestion and ICP-OES. Relative residue composition without residual-solid mass, a Mo mass balance or concentrate-specific phase/speciation evidence does not demonstrate Mo extraction or the authors' proposed sulfide-to-oxide conversion. No extraction percentage or recovered product is assigned to this concentrate. The 29.7% Mo result in Figure 7 and the SEM/XPS results in Figures 12 and 17 concern separate black-shale arms and cannot supply the missing concentrate evidence.
Figure 4a begins near pH 1.7 despite the methods' initial pH 1.4, and the reference electrode for its potential values is unspecified. The report calls WZ-Q moderately thermophilic in the concentrate methods but does not give that assay's temperature. These method and accounting limits prevent attributing the concentrate's compositional changes to microbial activity or treating them as a refutation of the bounded LR observation. Neither study establishes industrial deployment or universal molybdenite resistance to leaching under other conditions.

Sources & References

  1. ima_2026_09: IMA-CNMNC. The New IMA List of Minerals, September 2026. PDF page 146, Molybdenite row; page 1 column definitions and page 2 distribution terms.
    https://cnmnc.units.it/files/editor/IMA_Master_List_(2026-09).pdf (accessed 2026-10-11)
  2. francisco2007: Francisco Jr., Bevilaqua and Garcia Jr. (2007). Estudo da dissolucao oxidativa microbiologica de uma complexa amostra mineral contendo pirita (FeS2), pirrotita (Fe1-xS) e molibdenita (MoS2). Quimica Nova 30(5), 1095-1099. Complete publisher PDF, experimental methods and Figures 1-6.
    https://doi.org/10.1590/S0100-40422007000500008 (accessed 2026-10-11)
  3. francisco2007_supplement: Francisco Jr., Bevilaqua and Garcia Jr. (2007). Original supplementary page S1, Figures 1S-2S, appended to the complete article in the UNESP repository PDF. Figure 2S contains 43-day uninoculated controls.
    https://repositorio.unesp.br/server/api/core/bitstreams/4a0fec08-6d23-49aa-b365-0eff66bd691f/content (accessed 2026-10-11)
  4. ncbi_ferrooxidans: NCBI Taxonomy 920. Acidithiobacillus ferrooxidans, species-level entry; this identifier does not identify the experimental isolate LR.
    https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?id=920&mode=Info (accessed 2026-10-11)
  5. lu2026_concentrate: Lu et al. (2026). Influence and Mechanism of Vanadium, Nickel, and Molybdenum Bioleaching from Black Shale by Energy Substrates. Minerals 16(2), 197. Separate molybdenite-concentrate experiment, Table 2, Sections 2.2-2.4 and 3.3, Figure 4; Figures 7, 12 and 17 concern black shale instead.
    https://doi.org/10.3390/min16020197 (accessed 2026-10-11)

Curation History

Timestamp Curator Action Summary
2026-10-11T19:48:23.814621+00:00 codex (GPT-6; codex) CREATE Created mineral identity and a controlled limited-leaching observation, preserving censored Mo measurements, mixed-feed and companion-phase boundaries, source contradictions and the absence of demonstrated Mo recovery.
2026-10-11T19:54:08.466251+00:00 codex (GPT-6; codex) EDIT Addressed independent review F1 and issue 112 by retaining the source's temporal ambiguity instead of asserting a definite contradiction; all assay evidence remains unchanged.
2026-10-11T20:32:16.966796+00:00 codex (GPT-6; codex) EDIT Added the separate WZ-Q concentrate assay as context only, retaining residue-versus-solution ambiguity, missing controls and conditions, and the distinction from black-shale extraction results; existing LR science remains unchanged.

Record source: data/records/molybdenite.yaml