Alkali sulfates with aphthitalite-like structures from fumaroles of the Tolbachik volcano, Kamchatka, Russia. III. Solid solutions and exsolutions
Bibliographic record
Abstract
ABSTRACT Six different exsolution types are found in crystals of aphthitalite-group alkali sulfates from exhalations of the active Arsenatnaya fumarole, Tolbachik volcano, Kamchatka, Russia. The coexisting minerals in these exsolutions are metathénardite, ideally Na2SO4 (P63/mmc), and vanthoffite, Na6Mg(SO4)4 (P21/c) (Type I); metathénardite and belomarinaite, KNaSO4 (P3m1) (Type II); thénardite, Na2SO4 (Fddd), and aphthitalite, K3Na(SO4)2 (Pm1) (Type III); aphthitalite and arcanite, K2SO4 (Pnma) (Type IV); metathénardite and natroaphthitalite, KNa3(SO4)2 (Pm1) (Type V); and two chemical varieties of metathénardite (Type VI). The exsolution processes occur in crystals belonging to the high-temperature, hexagonal Na2SO4(I) (= metathénardite, P63/mmc) structure type with different K:Na ratios formed at temperatures higher than 500 °C. The similarity and hexagonal close-packed nature of the crystal structures of the coexisting phases, all representatives of aphthitalite-like structure types, cause the coherent conjugation of domains during diffusion and cation ordering in the parent phase. The breakdown of solid solution can be facilitated by the mosaic character of crystals of a parent phase (incoherent grain boundaries) and the presence of coherent twin boundaries. The heating of samples with exsolution Types II and V up to 700 °C over 24 h shows that diffusion of K and Na through the domain borders does not result in the complete disorder of these cations and the extinction of domains with different crystal structures.
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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 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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 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".