Goethite mineral
Goethite is the FeO(OH) mineral species listed as approved (A), with 1980 special-procedure history, in the IMA-CNMNC September 2026 master list. It is distinct from iron element, other iron oxyhydroxide minerals, iron-ore commodities and mixed goethite-bearing tailings. The natural mineral feeds below have sample-specific compositions; synthetic goethite preparations can contain more reactive precursor phases. No iron criticality designation is inherited.
Microbial & Biochemical Mechanisms (2)
Culture-associated iron mobilization from natural goethite during sulfur oxidation
bioleaching
Microbial
Associated Organisms:
Acidithiobacillus thiooxidans (NCBITaxon:930), Acidithiobacillus caldus (NCBITaxon:33059)
Separate living Acidithiobacillus thiooxidans DSM 14887 and Acidithiobacillus caldus DSM 8584 cultures increased filtered iron concentrations from a natural goethite feed while acidifying sulfur-containing medium. These laboratory observations support culture-associated mobilization. They do not isolate direct microbial reduction of solid goethite from acid dissolution or chemical reduction by sulfur intermediates.
Experimental Context & Analytical Limits:
Series 1 used BGR sample S343 from the Wolf mine, Herdorf, Germany, ground to a fine powder in a mortar. XRD with Rietveld refinement identified goethite as the mineral phase; the source calls it pure goethite, but Table 1 reports 85% Fe2O3 and 2% SiO2 by XRF, so chemical purity is not assumed. The cultures were precultivated for 10 days in HBS-TE medium at initial pH 3 with 1 g/L elemental sulfur and inoculated at 10% v/v into separate flasks containing 0.5% w/v S343 and 1 g/L sulfur. The aerobic five-week experiment used 30 degrees C and 120 rpm for A. thiooxidans and 45 degrees C shake-flask cultivation for A. caldus. Figure 1 shows starting pH near 3 in the dissolution assays. Three inoculated flasks were used per species; Methods 2.3 specifies duplicate uninoculated controls at each temperature, whereas Figure 1 caption describes three parallel assays each. Ferrozine analysis of 0.2 micrometre-filtered liquid measured Fe(II) and Fe(III). These are operationally filtered iron concentrations, not an isolated metal product or a whole-feed recovery yield. Species taxonomy identifiers do not independently identify the experimental DSM strains.
Series 1 used BGR sample S343 from the Wolf mine, Herdorf, Germany, ground to a fine powder in a mortar. XRD with Rietveld refinement identified goethite as the mineral phase; the source calls it pure goethite, but Table 1 reports 85% Fe2O3 and 2% SiO2 by XRF, so chemical purity is not assumed. The cultures were precultivated for 10 days in HBS-TE medium at initial pH 3 with 1 g/L elemental sulfur and inoculated at 10% v/v into separate flasks containing 0.5% w/v S343 and 1 g/L sulfur. The aerobic five-week experiment used 30 degrees C and 120 rpm for A. thiooxidans and 45 degrees C shake-flask cultivation for A. caldus. Figure 1 shows starting pH near 3 in the dissolution assays. Three inoculated flasks were used per species; Methods 2.3 specifies duplicate uninoculated controls at each temperature, whereas Figure 1 caption describes three parallel assays each. Ferrozine analysis of 0.2 micrometre-filtered liquid measured Fe(II) and Fe(III). These are operationally filtered iron concentrations, not an isolated metal product or a whole-feed recovery yield. Species taxonomy identifiers do not independently identify the experimental DSM strains.
Curated Evidence Points:
Support
Source:
stankovic_2024
Results 3.1 and Figure 1 report endpoint mean total iron concentrations of 1.9 mM with A. thiooxidans and 3.8 mM with A. caldus, compared with 0.08 mM and 0.3 mM in uninoculated controls at 30 and 45 degrees C, respectively. Culture pH reached 1.2 and 1.0, respectively. The paired temperature controls support conditional culture-associated mobilization; the different incubation temperatures prevent a species-only efficacy comparison.
Partial
Source:
stankovic_2024
No acid-matched or killed-cell Series 1 control separates acidity, reduced sulfur chemistry and cellular electron transfer. The Discussion explicitly states that changes in Fe(II)/Fe(III) alone cannot distinguish chemical sulfur-mediated reduction from dissimilatory ferric reduction. Figure 2 and the Discussion give different fitted correlation values; no numerical fit or direct causal proof is adopted here. The unresolved replication wording and lack of isolated product, full mass balance or industrial deployment limit interpretation.
No demonstrated enhancement of natural-goethite dissolution by Acidiphilium cryptum
bioleaching
Microbial
Associated Organisms:
Acidiphilium cryptum (NCBITaxon:524)
Under the tested anaerobic glycerol-fed conditions, living Acidiphilium cryptum DSM 2389 and SJH cultures reduced soluble ferric iron in positive controls but did not demonstrate enhanced iron extraction from the two natural goethite feeds relative to uninoculated controls. This is a condition-specific negative result, not a measured zero or a universal inability to transform goethite.
Experimental Context & Analytical Limits:
Series 3 used separately tested BGR S018 from Conakry, Guinea, and S337 from the Sasik mine, Pamir, Tajikistan. Both were mortar-ground and characterized by XRD/Rietveld analysis: S018 contained gibbsite and S337 contained 1% lepidocrocite. Table 2 gives BET areas of 35 and 19 m2/g, respectively. Five-day aerobic precultures were centrifuged, washed twice with medium and resuspended anaerobically for 10% v/v inoculation. Triplicate anaerobic unshaken assays at 30 degrees C used 0.1 g mineral (0.5% w/v), basal medium with yeast extract and 10 mM glycerol, initially adjusted to pH 2. Separate 25 mM ferric sulfate positive controls replaced the mineral; uninoculated controls were included. The experiment lasted 42 days, with 0.2 micrometre filtration and ferrozine iron assays. Transfer to fresh aerobic medium followed by nine-day cultivation and microscopy was used to check persistence of viable cells.
Series 3 used separately tested BGR S018 from Conakry, Guinea, and S337 from the Sasik mine, Pamir, Tajikistan. Both were mortar-ground and characterized by XRD/Rietveld analysis: S018 contained gibbsite and S337 contained 1% lepidocrocite. Table 2 gives BET areas of 35 and 19 m2/g, respectively. Five-day aerobic precultures were centrifuged, washed twice with medium and resuspended anaerobically for 10% v/v inoculation. Triplicate anaerobic unshaken assays at 30 degrees C used 0.1 g mineral (0.5% w/v), basal medium with yeast extract and 10 mM glycerol, initially adjusted to pH 2. Separate 25 mM ferric sulfate positive controls replaced the mineral; uninoculated controls were included. The experiment lasted 42 days, with 0.2 micrometre filtration and ferrozine iron assays. Transfer to fresh aerobic medium followed by nine-day cultivation and microscopy was used to check persistence of viable cells.
Curated Evidence Points:
Support
Source:
stankovic_2024
Results 3.3 and Figures 6-7 support the stated negative result: the authors report negligible extraction and no significant inoculated versus uninoculated difference for the natural feeds, while both strains reduced soluble Fe(III) in positive controls. Figure 9 includes small nonzero natural-feed iron concentrations; the narrative null is not converted into a zero concentration or an analytical detection limit.
Partial
Source:
stankovic_2024
Series 4 is a separate 33-day comparison involving S337 and synthetic preparations sG1/sG2, with a stated 13-day repeat; its endpoints must not be pooled with Series 3. The larger response for synthetic sG2 does not establish a pure-goethite mechanism. Synthetic BET areas of 62 and 97 m2/g exceed the natural values, and the authors infer more reactive ferrihydrite contamination without quantifying its phase fraction. Figure 8 contains finite natural-feed values despite the prose phrase not detectable. Neither the source's qualitative null nor its synthetic result establishes an absolute mineral-specific dissolution yield.
Sources & References
-
ima_2026_09: IMA-CNMNC master list, September 2026, PDF p84 Goethite row and p1 status definitions; retained official PDF reinspected 11 October 2026. The entry 1980 s.p. is special-procedure history, not an asserted external identifier.
https://cnmnc.units.it/files/editor/IMA_Master_List_(2026-09).pdf (accessed 2026-10-11) -
stankovic_2024: Stankovic S and Schippers A (2024). Goethite dissolution by acidophilic bacteria. Frontiers in Microbiology 15:1360018. DOI 10.3389/fmicb.2024.1360018; Methods 2.1-2.3, Tables 1-2, Results 3.1 and 3.3-3.4, Figures 1-2 and 6-9, Discussion and Conclusion. Publisher PDF and Europe PMC full-text XML inspected, including rendered PDF pp3-4 and 8-10.
https://doi.org/10.3389/fmicb.2024.1360018 (accessed 2026-10-11) -
ncbi_thiooxidans: NCBI Taxonomy 930, Acidithiobacillus thiooxidans; species-level taxonomy XML inspected.
https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?id=930 (accessed 2026-10-11) -
ncbi_caldus: NCBI Taxonomy 33059, Acidithiobacillus caldus; species-level taxonomy XML inspected.
https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?id=33059 (accessed 2026-10-11) -
ncbi_cryptum: NCBI Taxonomy 524, Acidiphilium cryptum; species-level taxonomy XML inspected.
https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?id=524 (accessed 2026-10-11)
Curation History
| Timestamp | Curator | Action | Summary |
|---|---|---|---|
2026-10-11T12:13:26.307790+00:00 |
codex (GPT-6; codex) | CREATE | Created goethite identity with natural-feed acidophile mobilization and condition-specific null evidence, preserving feed and causal limits. |
Record source: data/records/goethite.yaml