MONTBRAYITE, (Au,Ag,Sb,Pb,Bi)23(Te,Sb,Pb,Bi)38, FROM THE ROBB-MONTBRAY MINE, MONTBRAY, QU EBEC: CRYSTAL STRUCTURE AND REVISION OF THE CHEMICAL FORMULA
Bibliographic record
Abstract
The crystal structure of the mineral montbrayite, a rare gold telluride, was solved using intensity data collected from a crystal of the co-type material from the Robb-Montbray mine, Montbray, Abitibi County, Qu ́ebec, Canada. The study revealed that the structure is triclinic, space group P1, with cell parameters: a 10.8045(6), b 12.1470(6), c 13.4480(7) °A, a 108.091(5), b 104.362(5), c 97.471(5)8, and V 1583.65(15) °A3. The refinement of an anisotropic model led to an R index of 6.36% for 5145 independent reflections with Fo . 4r(Fo), GooF 1.023. There are 19 Te sites and 12 Au sites in the crystal structure of montbrayite. The Au sites host variable amounts of Sb, whereas all the Te sites but one host only Te. All the Au atoms can be considered to be in octahedral coordination forming more regular AuTe6 or more distorted AuTe4þ2 polyhedra, with the exception of one Au position which links five Te atoms and closes its coordination sphere with a contact with itself. Crystalchemical features of the Au and Te atoms are discussed in relation to other gold and silver tellurides. Electron microprobe analyses of the crystal used for the structural study led to the formula Au21.60Sb0.68Te37.41Bi1.31, calculated on the basis of 61 atoms per formula unit. On the basis of information gained from the structural and chemical characterization, the crystalchemical formula was revised, yielding (Au,Ag,Sb,Bi,Pb)23(Te,Sb,Bi,Pb)38 (Z 1⁄4 1) instead of (Au,Sb)2Te3 (Z 1⁄4 12) as previously reported. The redefinition of montbrayite has been approved by the Commission on New Minerals, Nomenclature and Classification of the International Mineralogical Association (voting proposal 17-F).
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.001 | 0.004 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.003 | 0.002 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".