Novel pathway of chalcopyrite formation at low temperature in microenvironments of acidic, metal-rich sediments
Bibliographic record
Abstract
Chalcopyrite (CuFeS2) is the main source of copper worldwide and is usually formed at high temperature. Its occurrence at low temperature is poorly documented, and the mechanisms controlling its formation remain uncertain. We found evidences of chalcopyrite formation in acidic pit lake sediments at ~ 12 °C. Using high-resolution electron microscopy and synchrotron-based spectroscopy, we observed aggregates of nanoscale crystals with the composition and structure of disordered chalcopyrite. Laboratory incubations at 20 °C and geochemical modelling suggest that microbial activity may contribute to chalcopyrite formation under these conditions. Particularly, crystal growth was associated with hollow structures resembling microbial cell surfaces, and on the membranes of eukaryotic-like cells, providing nucleation sites. Our findings suggest that microbial processes, including the production of hydrogen sulfide and the presence of organic surfaces, promote chalcopyrite formation at low temperature. This has implications for understanding copper and sulfur cycling and its potential biotechnological application in sulfidic environments. Chalcopyrite, the main copper ore mineral, is usually formed at high temperatures, according to a study that shows that microbial processes might promote its low-temperature formation in acidic pit lake sediments, with implications for bioremediation and biomining.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".