Sb5+ and Sb3+ substitution in segnitite: A new sink for As and Sb in the environment and implications for acid mine drainage
Bibliographic record
Abstract
A sample of Sb-rich segnitite from the Black Pine mine, Montana, U.S.A., has been studied by microprobe analyses, single-crystal X-ray diffraction, and μ-EXAFS and XANES spectroscopy. Linear combination fitting of the spectroscopic data provided Sb5+:Sb3+ = 85(2):15(2), where Sb5+ is in octahedral coordination substituting for Fe3+ and Sb3+ is in tetrahedral coordination substituting for As5+. Based upon this Sb5+:Sb3+ ratio, the microprobe analyses yielded the empirical formula Pb1.02 H1.02(Fe3+2.36Sb5+0.41Cu2+0.27)∑3.04(As5+1.78Sb3+0.07S6+0.02)∑1.88O8(OH)6.00. The crystal structure refinement and bond valence analysis are consistent with these cation site assignments. The formation of Sb-rich segnitite opens new possibilities for Sb sinks within the supergene zone. Segnitite may, in fact, be an ideal host for the sequestering of several toxic elements for pH < 2. At higher pH values, As is more likely to be incorporated into schwertmannite and ferrihydrite.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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) | 0.000 | 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 teacher head, 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".