Refinement of the crystal structure of zoned philipsbornite–hidalgoite from the Tsumeb mine, Namibia, and hydrogen bonding in the D<sup>2+</sup>G<sup>3+</sup><sub>3</sub>(T<sup>5+</sup>O<sub>4</sub>)(TO<sub>3</sub>OH)(OH)<sub>6</sub> alunite structures
Why this work is in the frame
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Bibliographic record
Abstract
Abstract The crystal structure of zoned philipsbornite – hidalgoite, hexagonal (rhombohedral), R m , Z = 3: a = 7.1142(4), c = 17.0973(9) A ˚ , V = 749.4(1) Å 3 , from the Tsumeb mine, Namibia, has been refined to R 1 = 1.68% for 301 unique reflections collected on a Bruker D8 three-circle diffractometer equipped with a rotating-anode generator, multilayer optics and an APEX-II CCD detector. Chemical analysis by electron microprobe showed zoned crystals with a rim enriched in S and Fe relative to the core. The core composition is SO 3 3.31, As 2 O 5 30.57, Al 2 O 3 23.05, FeO 1.44, PbO 33.94, H 2 O calc 9.58, total 101.79 wt.%, corresponding to Pb 0.98 2+ (Al 2.92 Fe 0.13 2+ )(AsO 4 )[(As 0.72 S 0.27 )O 3.14 (OH) 0.85 ](OH) 6 ; and the rim composition is SO 3 8.88, As 2 O 5 22.63, Al 2 O 3 22.90, FeO 2.57, PbO 34.91, H 2 O calc 9.27, total 101.16 wt.%, corresponding to Pb 0.99 2+ (Al 2.85 Fe 0.23 2+ )(AsO 4 )[(As 0.25 S 0.70 )O 3.30 (OH) 0.50 ](OH) 6 . Philipsbornite – hidalgoite has the alunite-type structure, sheets of corner-sharing octahedra, decorated on top and bottom by [(As,S)O4] and (AsO 3 OH) tetrahedra, that are linked into a three-dimensional structure by [12]-coordinated Pb 2+ cations and hydrogen bonds. A new hydrogen-bonding scheme for the D 2+ G 3 3+ (T 5+ O 4 )(TO 3 OH)(OH) 6 minerals is proposed.
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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 | 0.002 | 0.001 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.002 | 0.001 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.001 | 0.002 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.003 | 0.002 |
| Research integrity | 0.001 | 0.002 |
| 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 it