Short-range atomic arrangements in minerals. I: The minerals of the amphibole, tourmaline and pyroxene supergroups
Bibliographic record
Abstract
Spectroscopy is a key aspect of deriving local arrangements of atoms in minerals. Vibrational spectroscopy in the principal O–H-stretching region and MAS NMR spectroscopy are sensitive to such local arrangements, and play a crucial role in characterizing local structure in minerals in which there is solid solution. Variation in local arrangements of ions around a “probe” ion such as (OH)− can produce shifts in the energy of the principal O–H-stretching frequency, providing a window into those local arrangements. Similarly, variation in local arrangements around a “probe” isotope such as 27Al or 29Si can produce shifts in resonance energy that are indicative of differences in local environment. It is useful to develop a configuration symbol for the structural environment of the probe species, i.e. , the configuration of nearest-neighbour and next-nearest-neighbour polyhedra/sites, and then the local arrangements of atoms may be expressed in terms of this configuration symbol. Work on the monoclinic C 2/ m amphiboles, tourmaline and monoclinic pyroxene is reviewed here in terms of the particular effects that can give rise to absorptions in the principal O–H-stretching region of vibrational spectra. It is notable that the nearest-neighbour configurations in the amphibole, tourmaline and mica structures are topologically identical, and hence there should be strong spectral characteristics that are common to minerals of all three structure types. The spectra of the C 2/ m amphiboles show strong next-nearest-neighbour effects, and one expects such effects to occur also in spectra of minerals of the tourmaline (and mica) supergroups. The valence-sum rule of local bond-valence theory provides a strong constraint on possible local arrangements involved in heterovalent solid-solution in these minerals.
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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 | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 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".