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Cassiterite mineral

Cassiterite is the mineral species with IMA-approved formula SnO2. The September 2026 IMA list records grandfathered status G and original description year 1832; that year is not an IMA approval identifier. The mineral is distinct from elemental tin, a tin commodity, and a cassiterite-bearing experimental feed. The curated separation study used a Brazilian mineral sample reported as 84.7% pure by X-ray fluorescence, rather than a demonstrated pure SnO2 phase. No criticality designation is inherited from tin.

Microbial & Biochemical Mechanisms (1)

Biomass-associated surface modification and electroflotation of cassiterite fines

separation Microbial

Associated Organisms: Rhodococcus opacus (NCBITaxon:37919)

Prepared Rhodococcus opacus biomass was associated with adhesion, changed surface charge and increased hydrophobicity of a cassiterite sample. Laboratory electroflotation then collected part of the fine mineral feed without a conventional collector. The biomass was sterilized after cultivation and washing, so this is a microbial-origin reagent process, not demonstrated metabolic extraction. Surface-force and floc-size explanations remain interpretations; specific molecular binding and selective separation from gangue were not established in this article.

Experimental Context & Analytical Limits:
The culture came from the Andre Tosello collection in Sao Paulo; no strain accession is supplied. NCBITaxon:37919 identifies the named species only. Cells were grown for 48 h at 28 degrees C and 250 rpm in yeast/malt extract, peptone and glucose medium at initial pH 7.2, centrifuged, washed, resuspended in 0.1 mM NaCl and then sterilized for 20 min at the reported pressure of 1 atm. A viability assay or sterilization temperature is not reported. Dry mass, rather than a verified viable-cell count, quantified the preparation. The mineral came from Ze Estrada Mineracao, Minas Gerais, Brazil. Ground/sieved flotation fines were below 37 micrometres with reported d50 of 8 micrometres; the separate contact-angle assay used 106-210 micrometre particles. Flotation used a modified Hallimond tube with a stainless steel cathode and Ti/RuO2 anode, magnetic stirring, 1% pulp density and 0.1 M NaCl. The Methods specify 2 min conditioning, whereas the Results specify 5 min conditioning and 6 min flotation. Flotation tests were repeated twice, contact-angle measurements at least three times; these are not industrial trials. The mineral-free bubble-size assay used a separate 1 L cell. Surface and bubble comparisons include no-biomass conditions, but Figure 6 does not show a zero-biomass flotation arm. The article does not provide a recovered-tin mass balance, product grade or a detailed formula for its flotation recovery metric.
Curated Evidence Points:
Methods on pp. 508-509 and original Figures 2-5 support biomass-associated changes in surface charge, adhesion, contact angle and bubble size. Figure 4 compares untreated hydrophilic material with conditioned material; its coarse particle fraction differs from the flotation fines. Figure 5 measures bubbles without mineral. These observations support a surface-modifying reagent role, not a demonstrated enzyme, active uptake pathway or tin redox transformation.
The Results, Figure 6 and Conclusions report about 64.5% flotation recovery at the lowest plotted biomass concentration, stated as 50 mg/L, with lower recovery at higher doses. This is a reported mineral-flotation endpoint, not isolated tin yield. Figure 6 and the Results/Conclusions specify pH 3, but both abstracts specify pH 5 and 51.4 mA/cm2; the contradictory pH and 2-versus-5 min conditioning statements are not harmonized. The source's cell-count equivalents are also inconsistent: 600 mg/L is associated with 3.4e14 cells/mL in the electrokinetic Methods but 34.47e12 cells/mL in the contact-angle discussion. No conversion is repaired or adopted as a verified cell count. Missing zero-biomass flotation and gangue-selectivity results limit claims of microbial enhancement or a purified product.

Sources & References

  1. ima_2026_09: IMA-CNMNC. The New IMA List of Minerals, September 2026. PDF page 38, Cassiterite row; page 1, column definitions; page 2, distribution terms.
    https://cnmnc.units.it/files/editor/IMA_Master_List_(2026-09).pdf (accessed 2026-10-12)
  2. gonzales_2013: Valdiviezo Gonzales LG, Huaman Pino GA and Torem ML (2013). Electroflotation of cassiterite fines using a hydrophobic bacterium strain. REM: Revista Escola de Minas 66(4):507-512. DOI 10.1590/S0370-44672013000400016. Complete original pp. 507-512, Materials and methods, Results, Figures 1-6 and Conclusions.
    https://doi.org/10.1590/S0370-44672013000400016 (accessed 2026-10-12)
  3. ncbi_opacus: NCBI Taxonomy 37919, Rhodococcus opacus, species. Species mapping only; does not identify the experimental culture accession.
    https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?id=37919 (accessed 2026-10-12)

Curation History

Timestamp Curator Action Summary
2026-10-12T04:39:36Z codex (GPT-6) CREATE Added IMA-grounded cassiterite identity and qualified laboratory separation with sterilized Rhodococcus opacus biomass after complete primary-article and original-figure inspection. Preserved conflicting pH, conditioning and cell-count statements, unequal assay fractions, missing flotation controls and recovery limits.

Record source: data/records/cassiterite.yaml