A 57Fe MOSSBAUER SPECTROSCOPIC STUDY OF SUGILITE, KNa2(Fe3+,Mn3+,Al)2Li3Si12O30
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Bibliographic record
Abstract
Sugilite, ideally KNa(2)(Fe(3+),Mn(3+),Al)(2)Li(3)Si(12)O(30), from the Wessels mine, Kalahari, South Africa, was studied using (57)Fe Mossbauer spectroscopy. The spectra confirm published electron-microprobe data and X-ray single-crystal results, which indicate that Fe(3+) is ordered at the A octahedral site. The magnitude of the quadrupole splitting, DEQ for Fe(3+) at both 84 K and room temperature is 0.00 mm/s. This value is very low for a silicate; reported DEQ values for octahedrally coordinated Fe(3+) are generally greater than 0.20 mm/s. Octahedron distortion, calculated from published X-ray-diffraction data, gives an octahedron-angle variance of 7 and a mean elongation of the octahedron of 1.002. This indicates nearly regular octahedral geometry, and hence a symmetric electric-field gradient around Fe(3+). A crystal-chemical interpretation for the regular octahedral geometry and the resulting low DEQ value for Fe(3+) in the Mossbauer spectrum of sugilite is that structural strain is largely taken up by weak Li-O bonds. They permit highly distorted LiO(4) tetrahedra, whose variance in the O-Li-O angle, 502, and mean elongation of the tetrahedron, 1.148, are among the largest observed values for inorganic crystal structures. Weak Li-O bonds allow the edge-shared, more strongly bonded Fe(3+)O(6) octahedra to remain regular in geometry.
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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 | 0.000 |
| 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 | 0.000 |
| 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