FELBERTALITE AND RELATED BISMUTH SULFOSALTS FROM THE FUNIUSHAN COPPER SKARN DEPOSIT, NANJING, CHINA
Bibliographic record
Abstract
Electron-microprobe and single-crystal X-ray-diffraction analyses have confirmed the second occurrence of felbertalite in the Funiushan copper skarn deposit, near Nanjing, in eastern China. It can be chemically described as Cu2AgxPb6–2xBi8+x(S,Se)19, with a wide range of substitution of Bi + Ag for 2Pb, with x ranging from 0.64 to 1.03 (probably up to 1.33), suggesting the presence of a solid-solution series in felbertalite. The measured unit-cell parameters of a felbertalite grain with a composition of Cu2.20Ag0.70Pb4.65Bi8.45S19.12 are: a 27.68(4), b 4.046(1), c 20.67(3) Å, 131.06(8)°, space group C2/m. A set of phases in the bismuthinite–aikinite series, mostly free of Ag and characterized by intermediate compositions between ideal formulae, were identified with electron-microprobe data. Compositional variations from Cu1.80Pb1.80Bi2.20S6, through Cu1.53Pb1.53Bi2.47S6, Cu1.07Pb1.07Bi2.93S6, Cu0.73Pb0.73Bi3.27S6, to Cu0.58Pb0.58Bi3.42S6 within a single grain were observed, indicating that an intergrowth of three structural units, i.e., bismuthinite ribbons, krupkaite ribbons and aikinite ribbons, could occur in the progressive exsolution or precipitation of a single phase in the bismuthinite–aikinite series. The exceptionally high contents of Ag (0.76–1.27 wt%) in the phase Cu0.83Ag0.10Pb0.90Bi3.13S6, presumably corresponding to krupkaite, are noted. Electron-microprobe analyses have also revealed the occurrence of a number of rare minerals, including junoite, unknown Cu2AgxPb10–2xBi12+xS29 (1.23 < x < 1.49), berryite, benjaminite?, schirmerite?, Bi- and Ag-bearing galena, wittichenite and tetradymite. Within the intergrowths of Cu–Ag–
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.001 | 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) | 0.001 | 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 source (direct Gemma or distilled Codex), 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".