Crystal structure and topological affinities of magbasite, KBaFe<sup>3+</sup>Mg<sub>7</sub>Si<sub>8</sub>O<sub>22</sub>(OH)<sub>2</sub>F<sub>6</sub>: a trellis structure related to amphibole and carpholite
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Bibliographic record
Abstract
Abstract The crystal structure of magbasite from the Eldor carbonatite complex, Quebec, Canada, has been determined and indicates that the currently accepted formula should be revised to KBaFe 3+ Mg 7 Si 8 O 22 (OH) 2 F 6 . Magbasite is orthorhombic, space group Cmme ( Cmma ), with unit-cell parameters a 18.9506(3) Å, b 22.5045(3) Å, c 5.2780(1) Å, V 2250.93(6) Å 3 ( Z = 4). The structure has been solved and refined to final agreement indices R 1 = 0.026, wR 2 = 0.052, GooF = 1.116 for a total of 2379 unique reflections, and is a new kind of trellis motif related to amphibole and carpholite topologies. An amphibole-like I-beam ‖(100) of edge-sharing octahedrally-coordinated M (1,2,3) sites, which are filled by Mg, is sandwiched between double-chains of SiO 4 tetrahedra ‖c. This I-beam is connected to side-ribbons ‖(010) of edge-sharing (Mg,Fe 2+ )O 4 (OH,F) 2 and Fe 3+ O 4 (OH) 2 octahedra to form a tunnelled box or trellis structure very like that of carpholite, for which the I-beams are pyroxene-like. K occupies a tunnel site analogous to the A site of amphibole. Ba occupies a cavity site at the corners where the I-beam and side-ribbon meet, and corresponds to the A site of carpholite. The structural relations between magbasite and carpholite are discussed.
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.003 | 0.002 |
| Meta-epidemiology (broad) | 0.003 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.003 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.002 |
| Research integrity | 0.002 | 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