The crystal structure of launayite from Taylor Pit, Madoc, Ontario, Canada: crystal chemistry, modulated superstructures, and parent modular structure compared with rouxelite
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Bibliographic record
Abstract
Abstract. The crystal structure of launayite, ideally Cu2Pb20(Sb,As)26S60 (Z=4) from Taylor Pit, Madoc, Ontario, Canada, has been solved for the first time using the single-crystal X-ray diffraction (SCXRD) method. The mineral is composed of distinct superstructures that can be derived from the same parent structure. The structure of the main component is monoclinic and has been solved in the space group P2/a, with cell parameters a=42.6466(14), b=8.0381(2), c=34.3957(10) Å, β=64.684(2) °, and V=10 658.4(6) Å3 from an untwined crystal. The asymmetric unit of launayite contains 48 cation sites and 60 sulfur sites. Final refinement resulted in an R1 value of 0.0955 for 11 741 unique reflections. The structural formula obtained from SCXRD study is Cu2Pb20.330Sb23.024As2.689S60, Z=4, in agreement with the formula Cu2.078Ag0.059Tl0.057Pb20.404Sb22.830As2.772S59.80 from microprobe analysis. The structure of launayite can be viewed both as a boxwork structure and as a rod-based structure. The modular description of the launayite structure reveals a very close relationship with the structure of rouxelite: the parent structures of both can be regarded as merotypes. A full comparison of the crystal chemistry and modular description of both structures is presented.
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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) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 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 it