Controls on the Distribution of Gallium in the Nechalacho REE Deposit, NWT, Canada
Bibliographic record
Abstract
Despite the numerous industrial and scientific applications of gallium, its behavior in nature and the processes that concentrate it to potentially economic levels are poorly understood. Although the main supply of this metal is as a by-product of the mining of bauxite, it is also concentrated by magmatic-hydrothermal processes in peralkaline igneous systems. Here we report the results of a study of the distribution of gallium and the controls on this distribution in the Nechalacho rare metal deposit, Northwest Territories, Canada, which has been shown to contain significant reserves of this critical metal. Electron microprobe analyses and X-ray element maps of gallium-bearing minerals were used to determine the mineralogical distribution of gallium in the Nechalacho intrusive suite. Elevated gallium concentrations were identified in albite, biotite, orthoclase, chlorite, and allanite. Of these aluminum-bearing minerals, the most important hosts of gallium are albite, biotite, and orthoclase. Ferric iron-bearing minerals, including magnetite and aegirine, which were considered potential candidates for gallium sequestration, contain relatively low concentrations of the metal. This behavior of gallium, at least from a magmatic perspective, is consistent with its predicted partitioning between phenocrysts and melt. However, there is also evidence that gallium was redistributed by hydrothermal fluids. Chloritization of biotite resulted in the enrichment of gallium in the secondary mineral (chlorite), and the development of secondary albite (albitization) led to a depletion of gallium in primary albite. On the basis of these results, we argue that the overall distribution of gallium within the Nechalacho deposit was controlled by magmatic crystal fractionation, whereas hydrothermal processes led to local remobilization of the metal. During fractional crystallization, gallium was moderately compatible in minerals such as albite and biotite, whereas it bordered between compatibility and incompatibility in minerals such as magnetite and orthoclase, and was incompatible in aegirine. This resulted in a relatively constant bulk gallium concentration in the Nechalacho deposit, although locally, gallium was remobilized hydrothermally, particularly within the most altered parts of the intrusion, notably, the albitite.
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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 | 0.000 | 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".