Realgar mineral
Realgar is the monoclinic arsenic sulfide mineral, given as AsS in the September 2026 IMA list and represented molecularly as As4S4 in the selected primary study. The IMA entry is grandfathered, with original-description year 1747. It is distinct from elemental arsenic, orpiment, amorphous arsenic sulfides and other As4S4 polymorphs. No criticality designation is inherited from arsenic.
Microbial & Biochemical Mechanisms (1)
Culture-associated realgar alteration and transient arsenic mobilization
bioleaching
Microbial
Associated Organisms:
Acidithiobacillus ferrooxidans (NCBITaxon:920)
Living Acidithiobacillus ferrooxidans BY-3 cultures increased the reported peak aqueous arsenic concentration relative to a sterile control during laboratory leaching of a realgar-dominated natural powder with added ferrous sulfate. Surface alteration and changed residual mineral phases were observed. The later decline in aqueous arsenic, including concentrations below the sterile control, limits any claim of sustained extraction. Ferric-mediated dissolution and subsequent arsenic retention by secondary solids are interpretations, not separately isolated molecular pathways.
Experimental Context & Analytical Limits:
The source assigns BY-3 to an abandoned Baiyin, Gansu copper mine isolate and reports collection designation CCTCC-M203071; that designation is retained as a source statement, not an independently resolved strain ID. Inoculum volume, starting cell density and washed-cell status are not given in this article. Shimen, Hunan realgar was purified by a cited traditional method and crushed to 200 mesh, approximately 75 plus or minus 10 micrometres. Methods state 99.01% purity, whereas results and XRD assign 97 wt% realgar and 3 wt% arsenolite; these statements are not silently reconciled. Flasks of 250 mL contained 100 mL 9K medium, 0.5 g mineral and 44.69 g/L FeSO4.7H2O, initially pH 1.7 with sulfuric acid, at 30 degrees C and 150 rpm for 30 days. The basal medium per litre contained 3.0 g (NH4)2SO4, 0.1 g KCl, 0.5 g K2HPO4, 0.5 g MgSO4.7H2O and 0.01 g Ca(NO3)2. A sterile uninoculated flask was included under the same stated conditions; experiments were at least duplicated and reported as averages. No pH-matched time-course control, cell-contact separation or arsenolite-only control is reported. This is a laboratory mixed-mineral-feed observation, not an isolated arsenic-product yield or industrial deployment.
The source assigns BY-3 to an abandoned Baiyin, Gansu copper mine isolate and reports collection designation CCTCC-M203071; that designation is retained as a source statement, not an independently resolved strain ID. Inoculum volume, starting cell density and washed-cell status are not given in this article. Shimen, Hunan realgar was purified by a cited traditional method and crushed to 200 mesh, approximately 75 plus or minus 10 micrometres. Methods state 99.01% purity, whereas results and XRD assign 97 wt% realgar and 3 wt% arsenolite; these statements are not silently reconciled. Flasks of 250 mL contained 100 mL 9K medium, 0.5 g mineral and 44.69 g/L FeSO4.7H2O, initially pH 1.7 with sulfuric acid, at 30 degrees C and 150 rpm for 30 days. The basal medium per litre contained 3.0 g (NH4)2SO4, 0.1 g KCl, 0.5 g K2HPO4, 0.5 g MgSO4.7H2O and 0.01 g Ca(NO3)2. A sterile uninoculated flask was included under the same stated conditions; experiments were at least duplicated and reported as averages. No pH-matched time-course control, cell-contact separation or arsenolite-only control is reported. This is a laboratory mixed-mineral-feed observation, not an isolated arsenic-product yield or industrial deployment.
Curated Evidence Points:
Support
Source:
chen2012
Methods page 10 and results page 13 report soluble arsenic by ICP-AES. The culture reached 121.95 mg/L on day 15 compared with 16.44 mg/L in the sterile control, described as a 7.4-fold difference. Subsequently the culture concentration declined and by day 25 was lower than the control. These are the authors' solution concentrations, not a cumulative extraction fraction, mineral-specific arsenic mass balance or isolated recovery. The article supplies no concentration-time figure, numerical uncertainty for these values, or explicit liquid filtration specification.
Support
Source:
chen2012
Figures 1-3 and pages 11-14 document cracks or pits after extended culture exposure, starting-material realgar and arsenolite by XRD, and a realgar-associated Raman spectrum. Figure 2 and its discussion assign realgar, dimorphite, magnetite and jarosite to the bioleached residue. The reported 43, 23, 6 and 28 wt% are relative residual-solid phase assignments, not absolute product yields. Raman does not support the authors' tested pararealgar alternative; this does not establish the absence of every possible minor phase.
Partial
Source:
chen2012
A sterile control supports a culture-associated difference, but SEM attachment/surface changes do not isolate direct enzymatic attack from chemically mediated dissolution. Added medium iron and the arsenolite impurity prevent attributing all aqueous arsenic specifically to realgar or all secondary iron to the mineral. The proposed adsorption or coprecipitation explanation for declining aqueous arsenic is not tested with a closed arsenic balance or solid-phase arsenic speciation. Table 1 converts As/S ratios into normalized formulas inconsistently with its atom percentages; those formulas are not adopted as mineral stoichiometries.
Sources & References
-
ima_2026_09: IMA-CNMNC. The New IMA List of Minerals, September 2026. PDF page 183, Realgar row; page 1 column definitions. Retained original rechecked.
https://cnmnc.units.it/files/editor/IMA_Master_List_(2026-09).pdf (accessed 2026-10-14) -
handbook_realgar: Handbook of Mineralogy. Realgar, version 1 (2001-2005), one-page species entry with monoclinic cell and X-ray powder data.
https://handbookofmineralogy.org/pdfs/realgar.pdf (accessed 2026-10-14) -
chen2012: Chen, Yan, Wang, Li and Li (2012). Surface alteration of realgar (As4S4) by Acidithiobacillus ferrooxidans. International Microbiology 15, 9-15. Complete original; methods page 10, results pages 11-14, Figures 1-3 and Table 1.
https://doi.org/10.2436/20.1501.01.154 (accessed 2026-10-14) -
ncbi_ferrooxidans: NCBI Taxonomy 920. Acidithiobacillus ferrooxidans, species entry; not an identifier for the experimental strain BY-3.
https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?id=920&mode=Info (accessed 2026-10-14)
Curation History
| Timestamp | Curator | Action | Summary |
|---|---|---|---|
2026-10-14T13:09:55.722574+00:00 |
codex (GPT-6; codex) | CREATE | Created phase-grounded realgar record with sterile-control comparison, purity conflict, arsenolite impurity and later solution decline retained. |
Record source: data/records/realgar.yaml