CRYSTAL STRUCTURE AND MOSSBAUER SPECTROSCOPY OF TSCHERMAKITE FROM THE RUBY LOCALITY AT FISKENAESSET, GREENLAND
Bibliographic record
Abstract
The crystal structure of tschermakite from Fiskenaesset, Greenland, (K 0.05 Na 0.38 ) ∑0.43 (Ca 1.80 Na 0.05 Fe 2+ 0.15 ) ∑2.00 (Mg 3.65 Fe 2+ 0.18 Mn 0.03 Fe 3+ 0.09 Al 0.81 Cr 0.19 Ti 0.05 ) ∑5.00 (Si 6.43 Al 1.57 ) ∑8.00 O 22 [(OH) 1.95 F 0.04 Cl 0.01 ] ∑2.00 , a 9.8059(5), b 17.9721(8), c 5.3012(2) A, β 105.063(1)°, V 902.15 A 3 , space group C 2/ m , Z = 2, has been refined to an R 1 index of 3.2% using Mo K α single-crystal X-ray diffraction. The ratio Fe 3+ /Fe tot was determined by Mossbauer spectroscopy. The unit formula (calculated from the results of electron-microprobe analysis), the refined site-scattering values, observed average bond-lengths, and Mossbauer spectroscopy were used to assign site populations. Tetrahedrally coordinated Al occurs at both the T (1) and T (2) sites, but is strongly ordered at T (1), and [6] Al occurs at both the M (2) and M (3) sites, but is strongly ordered at M (2). Magnesium shows the site preference M (1) = M (2) > M (3), and higher-valence transition metals (Ti, Fe 3+ and Cr 3+ ) are ordered at M (2). The formula calculated from the electron-microprobe analysis showed an excess of C -group cations of 0.15 apfu , exactly in accord with the amount of Fe 2+ at M (4) indicated by Mossbauer spectroscopy. At the A site, Na was split between the A (2) and A ( m ) sites, and K was assigned to the A ( m ) site. We derived the short-range arrangements involving the M (4), O(3) and A sites, and calculated their relative fractions. As with other complicated monoclinic amphiboles, short-range order is common and dictated by the valence-sum rule of localized bond-valence theory.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.001 | 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) | 0.004 | 0.001 |
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 source (direct Gemma or distilled Codex), 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".