Comparative Raman and visible near‐infrared spectroscopic studies of jarosite endmember mixtures and solid solutions relevant to Mars
Bibliographic record
Abstract
The chemical, structural and spectral properties of hydrated sulfate minerals are essential for their potential identifications and better understanding of martian aqueous history. Jarosite is an indicator of wet and acidic conditions on Mars. However, whether jarosites exist as solid solution phases or physical mixtures of endmembers is still an open question. In this study, we focused on comparisons of spectral characteristics (X‐ray diffraction, Raman, Visible and Near‐infrared) between Jarosite Solid Solutions (JSS) and corresponding Jarosite Physical Mixtures (JPM) with different molar ratios of endmembers (i.e. K‐jarosite to Na‐jarosite), in order to quantitatively characterize their spectral differences and mixing effects. For both X‐ray diffraction and Raman spectra, we find JPM have more overlapped peaks than JSS due to physical mixing effects of the formers, and the relative intensity of the overlapped peaks in K–Na JPM is relevant to the percentage of endmembers. On the other hand, JSS and JPM have strikingly similar Visible and Near‐infrared spectral features except the absorption features at 1950 and 2225 nm, where JPM have larger absorption depth. The detailed spectra properties of these two series of jarosite samples would provide a valuable database for current orbital remote sensing detections and future in situ Raman investigations on Mars (e.g. ExoMars and Mars 2020). Copyright © 2017 John Wiley & Sons, Ltd.
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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 | 0.001 |
| 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 | 0.001 | 0.001 |
| 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".