The minerals of the kröhnkite supergroup: structural relations and chemical compositions
Bibliographic record
Abstract
Abstract The minerals of the kröhnkite, talmessite and fairfieldite groups plus dondoellite, general formula X 2 M 2+ (TO 4 ) 2 (H 2 O) 2 where X = Na, Ca; M 2+ = Mg, Fe, Mn, Co, Ni, Zn, Cu; and T = S, P, As; have been consolidated into the IMA-approved kröhnkite supergroup. The cell dimensions and space-group symmetries of the minerals in these three groups and dondoellite are distinct but the structures of these minerals are strongly related as they have topologically identical structural units. Differences in structure between the different groups involve the disposition of adjacent [M 2+ (TO 4 ) 2 (H 2 O) 2 ] chains and the stereochemical details of the hydrogen bonds that link adjacent [M 2+ (TO 4 ) 2 (H 2 O) 2 ] chains. The ions that form the interstitial complex of a mineral and the structural unit must satisfy the principle of correspondence of Lewis acidity–basicity whereby stable structures will form where the Lewis acidity of the structural unit closely matches the Lewis basicity of the interstitial complex. For pentavalent T cations (P 5+ or As 5+ ), the Lewis acidity of Ca 2+ shows the closest match of all cations to the Lewis basicity of the structural unit. For hexavalent T cations (S 6+ ), the Lewis acidity of Na + shows the closest match of all cations to the Lewis basicity of the structural unit.
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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 | 0.000 | 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".