HONGSHIITE, PtCu, FROM ITABIRITE-HOSTED Au Pd Pt MINERALIZATION (JACUTINGA), ITABIRA DISTRICT, MINAS GERAIS, BRAZIL
Bibliographic record
Abstract
Hongshiite occurs associated with palladian gold, and more rarely with native platinum, in the sulfide-free, hematite-rich jacutinga mineralization of the Quadrilatero Ferrifero, central Minas Gerais, Brazil. Hongshiite occurs in grains up to about 1.5 mm in cross-section. The crystals (>0.1 mm) are generally covered by a porous rim from which copper is preferentially leached, eventually forming a rind of nearly pure native platinum. The morphological and chemical features of hongshiite are similar to features caused by the weathering of primary gold in a lateritic environment. Submicrometer-sized crystals, acicular in shape, replace an octahedral precursor phase, interpreted to be magnetite. The magnetite could have acted as a local redox barrier to the passage of oxidizing hydrothermal fluids leading to hongshiite precipitation. Sperrylite, isomertieite, atheneite, sudovikovite, a “guanglinite”-like phase, an undefined copper selenide, and barite occur as euhedral to anhedral inclusions in the larger crystals of hongshiite. Patches of a Au–Cu–Pt alloy within hongshiite have a composition nearly intermediate between tetra-auricupride and hongshiite, and could be called platinian tetra-auricupride, suggesting an extension of a solid solution toward hongshiite. The presence of tiny rosette-like crystals of native palladium in the auriferous jacutinga mineralization is also documented.
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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 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".