CUPROMAKOPAVONITE, Cu8Ag3Pb4Bi19S38, A NEW MINERAL SPECIES, ITS CRYSTAL STRUCTURE AND THE CUPROPAVONITE HOMOLOGOUS SERIES
Bibliographic record
Abstract
Cupromakopavonite, ideally Cu8Ag3Pb4Bi19S38, is a new mineral species found in quartz veins at the scheelite deposit Felbertal, Salzburg Province, Austria. It is associated with makovickyite, oversubstituted krupkaite ( bd 55), hodrusite, and kupcikite. The mineral is opaque and grey with a metallic luster; it is brittle without any discernible cleavage. In reflected light, it is greyish white, the bireflectance is weak, and the anisotropy is moderate in air and strong in oil. Internal reflections are absent. The reflectance data (%, air) are: 42.9, 46.6 at 470 nm, 42.1, 46.5 at 546 nm, 41.3, 45.8 at 589 nm and 40.2, 45.1 at 650 nm. The average results of 15 electron-microprobe analyses are: Cu 7.29(6), Ag 5.48(4), Pb 8.84(14), Cd 0.39(6), Bi 59.9(2), S 17.90(6), total 99.80(23) wt.%, corresponding to Cu7.82Ag3.46Pb2.91Cd0.24Bi19.53S38.05 (on the basis of Me + S = 72 apfu ). The simplified formula, Cu8Ag3Pb4Bi19S38, is in accordance with the results of our crystal-structure analysis. The density, 6.85 g/cm3, was calculated using the ideal (structural) formula. Cupromakopavonite has a monoclinic cell with a 13.380(2), b 4.0007(6), c 31.083(4) A, β 93.064(2)°, V 1661.5(4) A3, space group C 2/ m , and Z = 1. The strongest eight lines in the (calculated) powder-diffraction pattern [ d in A(I) hkl ] are: 3.607(57)(207), 3.457(99)(114), 3.436(37)(208), 3.340(34)(401), 2.953(28)(311), 2.874(33) (2010), 2.834(100)(313) and 2.256(29)(1111). The crystal structure was refined to R = 4.53% and wR = 6.0% for 1834 reflections [ F o > 4σ( F o )]. Our crystal-structure determination reveals that the unusually high value of the c parameter results from: (1) regular alternation of pavonite-like N = 4 and N = 5 layers in the structure, (2) regularly oriented distribution of the pairs of Bi pyramids and pairs of Pb–Bi prisms in the thin slabs of the structure, and (3) the appearance of a new three-coordinated Cu site instead of the octahedrally coordinated Ag site in the thin slabs. Cupromakopavonite is the N = 4.5 member of the newly defined cupropavonite homologous series, and its name underscores its close structural relationships to its two neighboring members, cupromakovickyite (N = 4) and cupropavonite (N = 5). We define the structural and chemical properties of this series, with the general, ideal formula, Cu8Ag2N−6Pb4Bi2N+10S4N+20 for Z = 1, where N is the order of the homologue. It includes N = 7 (“cuproplumbian benjaminite”) and N = 8 (“cuproplumbian mummeite”).
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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 | 0.001 | 0.001 |
| 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) | 0.001 | 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".