THE THREE GENERATIONS OF GOLD IN THE PALAI-ISLICA EPITHERMAL DEPOSIT, SOUTHEASTERN SPAIN
Bibliographic record
Abstract
In the Palai‐Islica deposit, in southeastern Spain, gold is found associated with sulfide mineralization (particularly Fe sulfides). Grains of Au‐Ag alloy (gold of types A and B) occur with pyrite in mineralized veins, and grains of native gold (type C) are associated with areas of massive silicification at the uppermost levels of the deposit. The content of “invisible” gold in the various Fe sulfides is practically nil. Of all the textural varieties of pyrite studied, unzoned medium- to coarse-grained pyrite is the only one bearing gold. A clear distinction can be established between three types of gold (A, B and C), each with a different genesis. Grains of type-A alloy deposited as a result of variations in the thermodynamic parameters of the system, mainly a decrease in sulfur activity, whereas the appearance of the type-B alloy was mainly controlled by electrochemical factors. Type-C gold may have been produced from colloidal solutions in significantly different geochemical conditions. The chemical evolution of the alloys is characterized by Ag enrichment as precipitation continued. Type-A grains [mean Au/(Au + Ag) = 0.861] were the first to form, encased in the pyrite, with a relatively low Ag content and barely any zonation, followed by gold of type B, overgrowing pyrite, with a higher average Ag content [Au/(Au + Ag) = 0.756] and commonly zoned, with later zones richer in Ag. Finally, type-C native gold has practically no Ag [on average, Au/(Au + Ag) = 0.988].
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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 | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 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".