A CRYSTALLOGRAPHIC STUDY OF THE INCOMPLETE SOLID-SOLUTION BETWEEN PLUMBOJAROSITE AND JAROSITE
Bibliographic record
Abstract
An incomplete solid-solution series exists between jarosite, KFe 3 (SO 4 ) 2 (OH) 6 , and plumbojarosite, Pb[Fe 3 (SO 4 ) 2 (OH) 6 ] 2 , on the basis of experimental data and the observed chemical variations of these minerals in nature. Samples were synthesized in a chloride-rich solution at 140° and 110°C and studied using X-ray powder diffraction, Rietveld analysis and chemical analysis. Under these conditions, plumbojarosite will only precipitate if the solution has a high concentration of Pb, 99 mol.% Pb. Only jarosite forms from solutions with up to 79 mol.% Pb in the starting solution. At 85 mol.% Pb in the solution, both jarosite and plumbojarosite precipitate. At the conditions of synthesis, Pb substitution into jarosite is extremely limited, with occupancy of 2% in the potassium site. Increased Pb in the starting solution resulted in no increased substitution of Pb into jarosite, but an increased substitution of H 3 O + into the structure. An increase in charge due to Pb 2+ substitution at the A site causes a charge imbalance in the structure. Potassium substitution into plumbojarosite is more extensive, K/(Pb + K) = 32%. Potassium substitution preferentially occurs in one of the two symmetrically distinct A -sites, based on a Rietveld refinement of site populations.
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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 | 0.001 |
| 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) | 0.001 | 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".