Order-disorder, polytypes and twinning in the crystal structure of vurroite
Bibliographic record
Abstract
Vurroite, ideally Pb20Sn2(Bi,As)22S54Cl6, is a complex mineral type, where the two minor chemical components, Sn and Cl, act as essential constituents together with Pb, Bi, As and S 1, 2. X-ray single crystal data on vurroite strongly indicate an orthorhombic Fcentred symmetry 1, 3. In this study the crystal structure of vurroite is interpreted as an OD structure belonging to the category III of OD structures composed of equivalent layers 4. The application of the OD procedures allowed the derivation of the OD-groupoid family (λ and σ operations), as well as the MDO (Maximum Degree of Order) structures. The layer symmetry (λ) is A(2)mm, the interlayer symmetry (σ) consists of a glide plane n1/2,1/2 and two-fold screw axes parallel to 010 and 001 with the translation components ¼ b and ¼ c, respectively. For this OD family two MDO polytypes exists. The former has monoclinic symmetry, C12/c1, whereas the latter is monoclinic, P12/c1. The OD treatment of the crystal structure of vurroite allowed to prove that the true symmetry of this mineral is monoclinic and that the apparent orthorhombic symmetry observed for the X-ray pattern of the measured crystal is due to a twinning phenomenon. Prof. S. Merlino is gratefully acknowledged for his contribution on the OD interpretation of the structure of vurroite. 1 Pinto D., PhD thesis, University of Bari, 2004, 165. 2 Garavelli A.,Mozgova N.N., Orlandi P., Bonaccorsi E., Pinto D., Borodaev Y., Canadian Mineralogist, 2005, in press. 3 Pinto D., Balić-Žunić T., Bonaccorsi E., Makovicky E., 26th Nordic Geological Winter Meeting, Uppsala, Sweden,2004, 106-107, abstract. 4 Dornberger-Schiff K., Abh. Dtsch. Akad. Wiss. Berlin. Kl. Chem. Geol. Biol., 1964, 3, 1-107.
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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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| 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".