Triclinic titanite from the Heftetjern granitic pegmatite, Tørdal, southern Norway
Bibliographic record
Abstract
Abstract Two crystals from a sample of titanite from the Heftetjern granitic pegmatite, Tørdal, southern Norway, were extracted for structure analysis and shown to have triclinic symmetry. Unit-cell parameters are as follows:a= 7.0696(4) Å,b= 8.7167(5) Å,c= 6.5695(3) Å, α = 89.7372(11)°, β = 113.7607(10)°, γ = 90.2929(13)°,V= 370.52(6) Å3for one crystal anda= 7.0612(5) Å,b= 8.7102(6) Å,c= 6.5628(4) Å, α = 89.7804(16)°, β = 113.7713(13)°, γ = 90.2502(16)°,V= 369.39(7) Å3for the other. The interaxial angles α and γ deviate from the value of 90° required for monoclinic symmetry by ~200–250 standard deviations. The single-crystal X-ray intensities were averaged in both monoclinic and triclinic Laue symmetries, givingR(merge) values of ~14% and ~1.3% respectively. For both crystals, more than 50 reflections withI> 3σIviolated the criterion for the presence of thea-glide required for monoclinicA2/asymmetry. Both crystals were refined in the space groupA withZ= 4, and finalR1indices are 4.4% and 4.7% (wR2= 8.4 and 8.9%) respectively. The composition of one crystal was determined by electron microprobe analysis: Ca[Ti0.623Ta0.105Nb0.018Al0.137Fe0.0463+Sn0.0834+]Σ=1.012(SiO4)O. The characteristic corner-sharing [MO5] chains of identical octahedra observed in monoclinic titanite become chains of alternating M(1) and M(2) octahedra of different size, with the stronger X-ray scattering constituents concentrated at the M(2) site. Short-range bond-valence considerations suggest that theMcations will order as Al—O—Ta in adjacent octahedra, and when present in sufficient amounts, will couple along the chain to break long-range monoclinic symmetry.
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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 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| 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 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".