CMMMech
CMMMech > Mineral > Atacamite

Atacamite mineral

Atacamite is the orthorhombic copper hydroxychloride mineral Cu2Cl(OH)3. It is distinct from elemental copper, other copper minerals and mixed corrosion patinas. The laboratory mineral experiment below used a synthetic preparation. No criticality designation is inherited from copper.

Microbial & Biochemical Mechanisms (1)

Fungal-associated copper oxalate formation on synthetic atacamite

biomineralization Microbial

Associated Organisms: Beauveria bassiana (NCBITaxon:176275)

Laboratory cultures of Beauveria bassiana grew on synthetic atacamite-containing malt agar and the authors assigned copper oxalate products. This supports a qualified culture-associated transformation and precipitation observation. Acid-mediated dissolution followed by precipitation is a proposed explanation; neither causal necessity of oxalate nor isolated-metal recovery was established.

Experimental Context & Analytical Limits:
The live, unnamed Beauveria bassiana isolate came from copper-contaminated vineyard soil at Bevaix Abbey, Neuchatel, Switzerland. The article mentions a local collection deposit but supplies no accession; the species TaxID does not identify the isolate. Synthetic substrate was prepared using cited chemical methods, exposed to UV for 30 minutes and added after medium autoclaving. Malt agar contained 12 g/L malt and 15 g/L agar; incubation was at room temperature in the dark, with numerical temperature and pH unspecified. Five-mm square fungal plugs were used. Radial growth was followed in two perpendicular directions every 3-4 days over 18 days. The methods specify two or three replicates, whereas Figure 1 specifies three with standard errors. Figure 1 labels loadings 10, 20 and 50 g/L Cu(II) compounds, while the caption and prose vary between copper, Cu(II) and compound concentrations; no elemental-copper conversion is accepted. Copper-free malt agar was the growth comparison. No matched mineral-only sterile, killed-cell, pH-matched or acid-specific control is reported for this mineral assay. The silver-arm sterile control cannot be transferred. Separate product estimates used cultures after three months, dried at 60 degrees C, ground below 40 micrometres and pressed as 800-mg samples for Cu-K-alpha XRD, with a copper oxalate dihydrate/quartz calibration.
Curated Evidence Points:
Figure 1A and Results show growth at the labelled 10 and 20 g/L loadings, but full growth inhibition at 50 g/L atacamite. Figure 1B displays product estimates for the lower loadings; its missing 50-g/L bar is not treated as a measured zero product yield. The MATA series is named in text and Figure 1 but omitted from Table 1; no unstated standard MATA recipe is inferred.
Results page 5 assigns moolooite, CuC2O4.nH2O with n below 1, to products on all three copper media using ESEM, XRD and FTIR, partly referring to Joseph et al. 2011 for characterization. The complete 2012 article was inspected, but does not display the original powder patterns for these mineral arms. The accepted outcome is the authors' copper-oxalate product assignment, not independent confirmation of hydration, phase purity or complete substrate conversion. The related 2011 article's original graphics were not successfully acquired in this investigation and are not accepted as directly inspected evidence.
Figure 1B provides semiquantitative XRD estimates after three months. Its caption uses percentage of dry treated mycelium, while methods describe dried culture and Results use an ambiguous amount-of-copper denominator. The prose percentages are not unambiguously mapped to each mineral arm. No numerical extraction efficiency or recovered-product yield is imported; neither a copper mass balance nor purified product recovery was demonstrated.
Figure 3 and organic-acid methods concern separate mineral-free malt-agar cultures after 21 days at 8 or 12 g/L malt. Oxalic acid was detected among eleven acid standards. This supports an oxalate-producing phenotype, not proof that oxalate is the sole or necessary cause in the mineral arm. Reported production-rate units and extrapolated quantities are unresolved and are not imported or silently corrected. No industrial deployment or long-term conservation performance follows from these laboratory observations.
Context_only Source: ncbi_bassiana
The live authority resolves NCBITaxon:176275 to Beauveria bassiana at species rank. It does not verify the unnamed study isolate, strain accession or causal pathway.

Sources & References

  1. ima_2026_09: IMA-CNMNC. The New IMA List of Minerals, September 2026. Atacamite row, PDF page 17; introductory status definitions. G, 1797 denotes grandfathered status and original-description year, not an approval number.
    https://cnmnc.units.it/files/editor/IMA_Master_List_(2026-09).pdf (accessed 2026-10-15)
  2. handbook_atacamite: Handbook of Mineralogy. Atacamite, Cu2Cl(OH)3. Complete single-page identity, composition and crystallographic description.
    https://www.handbookofmineralogy.org/pdfs/atacamite.pdf (accessed 2026-10-15)
  3. joseph2012: Joseph et al. (2012). Protection of Metal Artifacts with the Formation of Metal-Oxalates Complexes by Beauveria bassiana. Frontiers in Microbiology 2:270; published 9 January 2012, eCollection 2011. Complete eight-page article, Table 1 and Figures 1-8, especially mineral assays in Figure 1 and separate acid assay in Figure 3.
    https://doi.org/10.3389/fmicb.2011.00270 (accessed 2026-10-15)
  4. ncbi_bassiana: NCBI Taxonomy 176275. Beauveria bassiana, species node.
    https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?id=176275 (accessed 2026-10-15)

Curation History

Timestamp Curator Action Summary
2026-10-15T00:08:15.724112Z codex (GPT-6; codex) CREATE Added atacamite mineral identity and qualified laboratory fungal-associated copper oxalate formation; preserved source concentration/product-denominator ambiguity and phase/control limits.

Record source: data/records/atacamite.yaml