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Ilmenite mineral

Ilmenite is the mineral species with ideal formula Fe2+Ti4+O3, listed with grandfathered status G and original description year 1827 by IMA-CNMNC in September 2026. The year is not an IMA approval number. The species is distinct from elemental titanium or iron, titanium commodities, ilmenite-bearing ores and concentrates, and manufactured titanium oxides. The primary dissolution study used three mixed placer concentrates dominated by ilmenite-like phases, not pure stoichiometric crystals. Its laboratory observation is scoped to those ground feeds. No criticality designation is inherited from titanium, and no microbial mechanism is accepted from the unavailable or insufficiently controlled bioleaching leads.

Microbial & Biochemical Mechanisms (1)

Laboratory HCl dissolution of ground ilmenite-bearing placer concentrates

other

Concentrated hydrochloric acid solubilized iron and titanium from ground ilmenite-bearing feeds. The authors fitted titanium dissolution to a shrinking-sphere model and observed faster dissolution in the feed with a lower Fe(III)/Fe(II) ratio. This comparison is an association across three chemically and texturally different concentrates, not an isolated causal test of iron valence. It does not demonstrate microbial action, isolated titanium product recovery, or industrial deployment.

Experimental Context & Analytical Limits:
Barrytown (BT), New Zealand concentrate was supplied by Rio Tinto; Kanyakumari (TIS) and Tuticorin (TVP), India concentrates were supplied by VV Minerals. Samples were disc-milled in 35 g batches for 2 min to broadly similar median particle sizes near 50 micrometres. Digestion used 38% w/w HCl at approximately 84 degrees C in a stirred 1.5 L round-bottom flask with reflux condenser. Acid was preheated to 40 degrees C before feed addition. The acid loading was reported as 6.12 mol HCl per mol calculated equivalent FeTiO3, not a claim that the mixed feed was pure FeTiO3. Actual digestion charge mass, working volume, stirring speed, replicate numbers and an acid-free dissolution control are not specified. Filtered aliquots were reduced with aluminium and titrated with cerium sulfate to determine dissolved Ti and Fe. The three feed trajectories are comparisons, not matched mineral-purity controls.
Curated Evidence Points:
Support Source: sun2025
Sections 2.3 and 3.3, Figure 3 and Equation 2 support time-dependent Ti and Fe solubilization in the stated laboratory arms and shrinking-sphere fits to titanium dissolution. The fitted ordering is BT faster than TIS faster than TVP. Dissolution curves, not recovered product mass, are the measured endpoint. The authors interpret the absence of a decline in dissolved Ti as no Ti hydrolysis during digestion; that trajectory alone does not establish an independently measured zero amount of solid secondary Ti product.
Partial Source: sun2025
Sections 3.2, 3.4-3.5, Table 1 and Figures 2, 4-6 constrain the iron-valence interpretation. Feed bulk analyses came from suppliers for TIS/TVP and an earlier publication for BT, rather than new independent bulk assays in this study. Inclusions and mineral intergrowths differ, so the correlation does not establish a universal rate law for pure ilmenite. The TIS XANES pre-edge centroid depends on imposed fit constraints and is explicitly unreliable; its uncertainty is ill defined. Section 2.4 calls kinetic fit uncertainties standard errors whereas section 3.3 calls them standard deviations. No numerical precision or population-wide rate advantage is adopted. The paper itself says the molecular reason for slower dissolution with higher oxidation remains unresolved; no hard-rock feed was tested.

Sources & References

  1. ima202609: IMA-CNMNC. The New IMA List of Minerals, September 2026. Species row on PDF page 100; status and column definitions on pages 1-2.
    https://cnmnc.units.it/files/editor/IMA_Master_List_(2026-09).pdf (accessed 2026-10-16)
  2. sun2025: Sun TY, Wykes JL, Wolmarans K, Kappen P, Haverkamp RG. The Dependence of Ilmenite’s Dissolution Rate in Hydrochloric Acid on the Fe(III)/Fe(II) Ratio, with Fe K-Edge XANES Pre-Edge Peak Analysis. Minerals 15(1):20 (2025 issue; published 27 December 2024). DOI 10.3390/min15010020. Complete ten-page original; sections 2.1-2.5 and 3.1-3.5, Table 1 and Figures 1-6.
    https://doi.org/10.3390/min15010020 (accessed 2026-10-16)

Curation History

Timestamp Curator Action Summary
2026-10-16T06:52:50Z codex (GPT-6; codex) CREATE Created distinct IMA-grounded Ilmenite species with qualified primary laboratory acid-dissolution evidence and explicit feed, fit, control and recovery limits.

Record source: data/records/ilmenite.yaml