Precious metal abundances in selected iron meteorites; in-situ AMS measurements of the six platinum-group elements plus gold.
Bibliographic record
Abstract
Abstract We have measured the abundances of seven precious metals in NiFe phases (kamacite and plessite) in six iron meteorites. These in-situ analyses, obtained by accelerator mass spectrometry (AMS) on small polished samples previously characterized by electron microprobe techniques, constrain the distribution of the rare siderophile elements. Within our set of irons, a small but varied suite, concentrations measured by AMS vary by factors of 9–13 for Au, Pd, Pt, Rh and Ru, and by factors of 90 and 250 for Ir and Os respectively. Data are presented for all six platinum group elements (PGE) plus gold. The AMS data suggest a variation in overall precious-metal abundances of a factor of 16 between the most-enriched (Negrillos, Σ PGE + Au = 270 ppm) and the least-enriched (Welland, 16–19 ppm). A clear illustration of the use of AMS data for provenance studies of meteoritic iron is presented for the Welland IIIA iron, an 1888 find from Ontario. Few published data are available for Welland: comparison of a type sample with a smaller piece of unknown metal, with respect to chondrite-normalized PGE patterns, major-element chemistry and textures of the metals, strongly support a suggestion that the latter is a fragment of the same iron.
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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 | 0.001 |
| 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) | 0.000 | 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".