Cuprite mineral
Cuprite is the cubic copper(I) oxide mineral Cu2O, listed as grandfathered in the September 2026 IMA compilation. It is distinct from elemental copper, tenorite (CuO), copper oxalates and heterogeneous copper ores. The experiment below used a commercial Cu2O preparation, not a natural ore specimen. No criticality designation is inherited from copper.
Microbial & Biochemical Mechanisms (1)
Fungal-associated alteration of commercial cuprite-form copper oxide
bioleaching
Microbial
Associated Organisms:
Beauveria caledonica (NCBITaxon:38006)
Laboratory cultures inoculated with Beauveria caledonica cleared an initially opaque Cu2O-containing agar and produced organic acids in a separate liquid Cu2O experiment. The authors also report copper oxalate hydrate formation from the copper substrates. These observations support culture-associated alteration with a proposed ligand-promoted pathway; they do not isolate oxalate as a necessary cause, determine a copper oxidation pathway, or establish complete copper extraction or an isolated product recovery yield. No industrial deployment was tested.
Experimental Context & Analytical Limits:
The source's unnamed isolate came from lawn soil in the United Kingdom via the CEH Merlewood collection. An approximately 550-base ITS sequence was reported as 99 percent similar to U19043; that historical reference accession does not identify the experimental isolate. Commercial BDH Cu2O was heat sterilized at 95 degrees C for 36-48 hours. Its starting phase purity and particle size were not reported; a starting-material diffraction check described for pyromorphite must not be transferred. Modified Melin-Norkrans medium contained, per litre, glucose 10 g, (NH4)2HPO4 0.5 g, KH2PO4 0.3 g, MgSO4.7H2O 0.14 g, CaCl2.6H2O 0.05 g, NaCl 0.025 g, glutamic acid 0.001 g and thiamine 0.0001 g; solid medium additionally contained agar 14 g. The initial pH was adjusted to 5.5 before autoclaving. Agar assays used 20 mL medium in 90-mm dishes with 7.5 mM Cu2O, equivalent to 15 mM copper atoms, a cellophane membrane and a 7-mm inoculum disc from a culture at least 14 days old. Incubation was at 25 degrees C with colony and clear-zone monitoring over two months. Methods specify at least three replicates; Figure 1 states at least four determinations. Separately, static liquid cultures used 12 mL medium in 50-mL flasks with the same Cu2O loading and inoculum at 25 degrees C for 60 days, with at least three replicates. Liquid organic acids were assayed by HPLC and oxalate also by an enzymatic method. A Cu2O-specific pH trajectory and matched acid-only, killed-cell or pH-matched controls were not reported. Mineral-free inoculated medium was a comparison.
The source's unnamed isolate came from lawn soil in the United Kingdom via the CEH Merlewood collection. An approximately 550-base ITS sequence was reported as 99 percent similar to U19043; that historical reference accession does not identify the experimental isolate. Commercial BDH Cu2O was heat sterilized at 95 degrees C for 36-48 hours. Its starting phase purity and particle size were not reported; a starting-material diffraction check described for pyromorphite must not be transferred. Modified Melin-Norkrans medium contained, per litre, glucose 10 g, (NH4)2HPO4 0.5 g, KH2PO4 0.3 g, MgSO4.7H2O 0.14 g, CaCl2.6H2O 0.05 g, NaCl 0.025 g, glutamic acid 0.001 g and thiamine 0.0001 g; solid medium additionally contained agar 14 g. The initial pH was adjusted to 5.5 before autoclaving. Agar assays used 20 mL medium in 90-mm dishes with 7.5 mM Cu2O, equivalent to 15 mM copper atoms, a cellophane membrane and a 7-mm inoculum disc from a culture at least 14 days old. Incubation was at 25 degrees C with colony and clear-zone monitoring over two months. Methods specify at least three replicates; Figure 1 states at least four determinations. Separately, static liquid cultures used 12 mL medium in 50-mL flasks with the same Cu2O loading and inoculum at 25 degrees C for 60 days, with at least three replicates. Liquid organic acids were assayed by HPLC and oxalate also by an enzymatic method. A Cu2O-specific pH trajectory and matched acid-only, killed-cell or pH-matched controls were not reported. Mineral-free inoculated medium was a comparison.
Curated Evidence Points:
Support
Source:
fomina2005
Figure 1B and Results describe full-plate clearing around fungal growth on Cu2O-containing agar. This is the visual solubilization criterion used by the authors, not a complete copper mass balance or measured 100-percent metal recovery. Figure 1A is a fungal biomass tolerance ratio against mineral-free medium, not an extraction yield. Figure 2C shows Cu2O-associated mycelial morphology after three weeks. Figure 3C demonstrates oxalate and citrate production in the separate liquid experiment; Figure 3A shows acids in the mineral-free fungal culture.
Partial
Source:
fomina2005
Figure 5B and the Results assign copper oxalate hydrate (moolooite, PDF 21-0297) to products from copper phosphate or cuprite. The displayed trace has a shared substrate caption rather than a separately labelled cuprite trace. It therefore supports the authors' reported product assignment with limited arm-specific traceability, not a quantified cuprite-to-pure-moolooite conversion, hydration measurement or yield. Copper-phosphate-arm electron microscopy, X-ray absorption measurements and biomass copper quantities are not transferred to the Cu2O arm.
Partial
Source:
fomina2005
Organic acid production and the reported oxalate product are consistent with the proposed ligand-promoted pathway, but do not separate oxalate, citrate, proton attack and other culture effects. The abiotic oxalic acid dissolution comparison in this paper concerns phosphate substrates, not Cu2O. Neither a Cu(I)-to-Cu(II) electron balance nor a causal enzyme experiment is provided for cuprite. The endpoint of the Figure 1 summary is not explicitly stated beyond the incubation protocol.
Context_only
Source:
ncbi_caledonica
The authority verifies the species label and TaxID, not the identity or activity of the unnamed experimental isolate.
Context_only
Source:
reference_its
U19043.1 is a historical species reference whose direct-submission entry gives a National Taiwan University address. No specimen-country qualifier is supplied. The study compared its UK isolate to this accession; it did not deposit that isolate under this identifier.
Sources & References
-
ima_2026_09: IMA-CNMNC. The New IMA List of Minerals, September 2026. Cuprite row, PDF page 52; introductory status definitions. G is grandfathered; 1845 is an original-description year, not an IMA approval number.
https://cnmnc.units.it/files/editor/IMA_Master_List_(2026-09).pdf (accessed 2026-10-14) -
handbook_cuprite: Handbook of Mineralogy. Cuprite, Cu2O. Single-page species description, cubic structure, powder reference and geological occurrence.
https://www.handbookofmineralogy.org/pdfs/cuprite.pdf (accessed 2026-10-14) -
fomina2005: Fomina et al. (2005). Role of Oxalic Acid Overexcretion in Transformations of Toxic Metal Minerals by Beauveria caledonica. Applied and Environmental Microbiology 71:371-381. Complete article, Methods and Results, Figures 1-7; Cu2O-specific Figures 1, 2C, 3C and shared Figure 5B.
https://doi.org/10.1128/AEM.71.1.371-381.2005 (accessed 2026-10-14) -
ncbi_caledonica: NCBI Taxonomy 38006. Beauveria caledonica, species node.
https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?id=38006 (accessed 2026-10-14) -
reference_its: GenBank U19043.1. Beauveria caledonica ribosomal and ITS sequence, 630 bases; historical reference sequence used for the study's comparison, not a deposition of its experimental isolate.
https://www.ncbi.nlm.nih.gov/nuccore/U19043.1 (accessed 2026-10-14)
Curation History
| Timestamp | Curator | Action | Summary |
|---|---|---|---|
2026-10-14T22:54:27Z |
codex (GPT-6; codex) | CREATE | Added cuprite identity and qualified fungal-associated commercial Cu2O alteration, separating clearance and acid assays from mass-balanced extraction, product recovery and copper-phosphate-arm measurements. |
2026-10-14T22:59:22.562183+00:00 |
codex (GPT-6; codex) | EDIT | Corrected U19043.1 geographic provenance to its submission address, leaving specimen origin unrecorded after independent review finding CMMMech.cuprite.reference-sequence-taiwan-provenance. |
Record source: data/records/cuprite.yaml