Mineralogy of complex Co-Ni-Bi vein mineralization, Bieber deposit, Spessart, Germany
Bibliographic record
Abstract
Abstract Post-Variscan vein-type Co-Ni-Bi ores of the Bieber deposit, Spessart mountains, Germany, which are related to the Permian Kupferschiefer, have been investigated by ore microscopy, X-ray powder diffraction and electron-probe microanalysis. The samples contain a variety of ore minerals, notably skutterudite, native bismuth, cobaltite, alloclasite, niccolite, maucherite, gersdorffite, rammelsbergite/pararammelsbergite, safflorite, loellingite and emplectite. The ores display structures indicative of multiple brecciation and complex zoned arsenide assemblages. Three sequential stages of deposition are identified, which are (1) the Cu stage, (2) the main Co-Ni-Bi stage, and (3) the late stage. The arsenide minerals, notably skutterudite, diarsenides and sulpharsenides, show a large range of compositional variation in Co-Ni-Fe space. A relatively limited number of skutterudite and diarsenide compositions lie outside the compositional fields established in the literature. Skutterudite and diarsenides are characterized by a significant substitution of As by S up to 0.44 a.p.f.u. and 0.31 a.p.f.u., respectively, which is larger than the range previously reported for these minerals. Sulpharsenide compositions can be grouped into three populations, which conform to cobaltian arsenopyrite, cobaltite and gersdorffite. They display highly variable As/S ratios between 0.95:1.00 and 1.29:0.73, consistent with experimental data. Estimates of the formation temperatures, based on the presence of dendritic native bismuth and emplectite, are in the range 100–300°C, similar to different post-Variscan mineralization styles widespread in Central Europe. Comparison of the Co-Ni-Bi vein assemblage with the framework of available paragenetic information and radiometric age data for regional mineralization events indicates an age of mineralization of ~150–160 Ma for the Bieber deposit.
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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 | 0.002 | 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".