GERMANIUM-BEARING COLUSITE FROM THE WATERLOO VOLCANIC-ROCK-HOSTED MASSIVE SULFIDE DEPOSIT, AUSTRALIA: CRYSTAL CHEMISTRY AND FORMATION OF COLUSITE-GROUP MINERALS
Bibliographic record
Abstract
Bornite-bearing ores of the Waterloo volcanic-rock-hosted massive sulfide (VHMS) deposit, northern Queensland, Australia, host germanium-bearing colusite, ideally Cu24+xV2(As,Sb)6‐x(Sn,Ge)xS32, which has been studied by a combination of reflectedlight microscopy, scanning electron microscopy and electron-microprobe (EMP) analysis. On the basis of textural criteria, colusite is associated with pyrite, chalcopyrite, sphalerite, tennantite and bornite. The EMP investigations showed that the colusite is chemically homogeneous, the concentrations of As, Sb, V, Sn and Ge being in the range of 3.42‐4.08, 0.10‐0.20, 1.86‐2.19, 0.01‐0.12 and 1.78‐2.23 apfu, respectively. Data analysis demonstrates a statistically significant negative correlation between (As + Sb) and (Ge + Sn), in apfu. Moreover, the nominal number of vacancies per formula unit (pfu), calculated as 34 ‐ cations apfu, was found to correlate negatively with (Cu + Fe + Zn). A compilation of literature data supports the existence of these two compositional trends in colusite-group minerals. However, the calculated nominal number of vacancies ranges between ‐2.0 and 2.5 pfu, indicating a significant deviation from the ideal crystal-chemical formulae proposed so far. The compositional range of the literature data can only be explained by the simultaneous operation of at least three different schemes of coupled substitution. Compositional discontinuities in the quaternary system As‐Sb‐Sn‐Ge are interpreted to be indicative of the existence of miscibility gaps in the colusite group. Integration of the results of the present study and literature data with phase-equilibria constraints suggests that colusite-group minerals in VHMS deposits form under moderately oxidized conditions at distinctly high Cu:Fe activity ratios in the ore-forming hydrothermal fluids.
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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 | 0.000 | 0.000 |
| 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 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".