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Heterogenite mineral

Heterogenite is the cobalt(III) mineral with ideal formula CoO(OH), recorded as approved, 1967 special procedure, in the September 2026 IMA list. The Handbook describes 3R and 2H polytypes; neither is assigned to the experimental ore below. It is distinct from elemental cobalt, other cobalt minerals and an entire copper-cobalt ore. The accepted primary experiment concerns chemical leaching of mixed natural ore whose cobalt-bearing mineral was assigned to heterogenite by QEMSCAN. It does not demonstrate microbial participation, a pure-phase dissolution yield or an inherited criticality designation.

Microbial & Biochemical Mechanisms (1)

Chemical reductive leaching of heterogenite-bearing mixed ore

redox transformation

Sodium sulphite added during agglomeration was associated with lower solution redox potential and greater elemental cobalt dissolution during acid percolation through mixed copper-cobalt ore. The authors interpret this as reductive dissolution of cobalt(III)-bearing heterogenite. No organism or biomass was introduced, and the study does not isolate a mineral-specific rate, prove a unique microscopic pathway or produce a recovered cobalt product.

Experimental Context & Analytical Limits:
Experimental, PDF pages 2-4: an unspecified DRC copper-cobalt oxide ore was crushed to 100% below 25 mm, blended and split into 30 kg batches. The actual mass loaded in each column is not specified. Head assays report 0.29% Co, 3.60% Cu, 3.53% Fe and 6.81% carbonate. QEMSCAN of a 100% below 0.3 mm head sample assigned cobalt to heterogenite in an ore containing several copper minerals; no powder diffraction, polytype assignment or quantitative heterogenite abundance is shown. Six water-jacketed polypropylene columns were 1 m tall and 160 mm inside diameter, operated at 25 degrees C. Table 1 gives 8% agglomeration moisture, 24 kg H2SO4 per tonne ore, and reductant doses 0, 0.5, 1 or 5 kg SO3 per tonne supplied as Na2SO3, not kg Na2SO3 per tonne. C1-C4 used three-day curing and open irrigation with 7 g/L H2SO4 at 6 L/m2/h. C5 used the same 5 kg SO3/t dose and three-day curing but returned copper-solvent-extraction raffinate after acid readjustment to 7 g/L. C6 used 5 kg SO3/t and seven-day curing with open irrigation. Water washing started on day 181 except C6, day 177. No independent replicate columns, inoculated comparison or microbial assay is reported.
Curated Evidence Points:
Experimental and Results, PDF pages 3-9, Table 1, Figures 3-5 and Table 4 support the stated dose and circuit comparisons. Table 4 reports cobalt dissolution of 43.1% for C1 without sulphite, 50.6% for C2 at 0.5 kg SO3/t, 54.0% for C3 at 1 kg SO3/t, and 60.8% for C4 at 5 kg SO3/t, all with three-day curing and open irrigation. C5 closed-circuit recycling gives 79.4%; its changed circuit is explicit and is not treated as an otherwise identical dose replicate. The percentages use a recalculated elemental head grade derived from solid and solution accounting over leaching, washing and drain-down, not an independently measured heterogenite fraction or an isolated cobalt-product recovery denominator.
Results, PDF page 6 and Figure 5: C5's temporarily negative calculated cobalt dissolution follows return of raffinate with a higher cobalt concentration than bed solution; the calculation subtracts irrigation cobalt from pregnant-solution cobalt. It is not direct evidence of cobalt precipitation. The proposed return of unreacted sulphite or other reductants, including ferrous iron, is an explanation for lower potential, not a demonstrated exclusive cause. Redox potentials use a 3 M KCl Ag/AgCl reference, not the standard hydrogen electrode.
Table 4 gives 62.8% cobalt dissolution for seven-day-cured C6 versus 60.8% for three-day-cured C4. The authors' statement that longer curing had no effect is descriptive, without reported independent replication or a statistical equivalence test. The abstract's rounded 62% for the 5 kg SO3/t open-circuit condition does not replace the arm-specific values. Table 4 and Figure 6 show copper dissolution between 90.3% and 94.6%, including 91.0% without sulphite; cobalt enhancement does not imply a corresponding large copper benefit.
Recipe and analytical reporting are incomplete. PDF page 3 describes dissolving Na2SO3 in 7 g/L acid before wetting to 8% moisture, whereas Table 1 separately gives 24 kg acid/t in agglomeration; the text does not explain how these acid additions relate. The solution-analysis paragraph lists daily Cu/Fe AAS and a monthly ICP-OES suite that omits Co despite reported solution cobalt, so its analytical schedule is unresolved. The mine, loaded mass, cobalt valence-specific assay and independent column uncertainties are not supplied. These are laboratory column results, not verified heap deployment; the conclusion's broad recovery wording does not establish cobalt separation or product purity.

Sources & References

  1. ima_2026_09: IMA-CNMNC. The New IMA List of Minerals, September 2026; Heterogenite row, PDF page 93, and pages 1-2 definitions. Status A and 1967 s.p.
    https://cnmnc.units.it/files/editor/IMA_Master_List_(2026-09).pdf (accessed 2026-10-15)
  2. handbook: Handbook of Mineralogy. Heterogenite, version 1 (2001-2005); complete one-page entry, Co3+O(OH) formula and 3R/2H polytype descriptions.
    https://www.handbookofmineralogy.org/pdfs/heterogenite.pdf (accessed 2026-10-15)
  3. ndhlalose2023: Ndhlalose, M., Basson, P., Robertson, S. and Nxumalo, N. (2023). Reductive Percolation Leaching of a Copper-Cobalt Ore. Part I: Sodium Sulphite as Reducing Agent. ALTA 2023 Nickel-Cobalt-Copper Conference, Mintek contribution; complete ten-page original, Figures 1-6 and Tables 1-4.
    https://d3e2i5nuh73s15.cloudfront.net/wp-content/uploads/2023/04/ALTA-2023-NCC-1-Paper-Mintek-Part-1.pdf (accessed 2026-10-15)

Curation History

Timestamp Curator Action Summary
2026-10-15T02:28:43Z codex (GPT-6; codex) CREATE Created a distinct heterogenite owner from complete primary abiotic mixed-ore percolation evidence and mineral authorities, retaining polytype, dose, circuit, denominator, replication and recipe limitations; microbial originals remain deferred.

Record source: data/records/heterogenite.yaml