CONDENSATE MINERALS FROM A BURNING COAL-WASTE HEAP IN AVION, NORTHERN FRANCE
Bibliographic record
Abstract
A coal-waste heap in Avion, northern France, that has been undergoing subsurface combustion for several decades, is marked by the occurrence of efflorescences at combustion sites where gas and water vapor escape from surficial cracks and vents. Analysis of the efflorescences show that twenty different species of mineral are present, comprising various sulfates, as well as halides and native sulfur. The constituents needed for the formation of these minerals are ultimately derived from the heap of coal-mine waste, composed mainly of pyrite-bearing carbonaceous shale, coal and minor amounts of sandstone. They may be partly released by acid weathering of waste-heap materials prior to combustion, but largely by thermal decomposition and oxidation of those materials during combustion processes. Formation of the efflorescences near gas-discharge zones indicates transport of constituent to those zones from the inner part of the waste heap, which can occur in the gas phase for some elements (S, N, H and Cl), but would require droplets of water vapor as carriers for most cations. Interaction between condensate solutions and the local debris at the surface of the waste heap may also contribute to cations input prior to the formation of secondary minerals. Most minerals formed from a liquid phase along the rock-debris surface at low temperatures (T ≤ 100°C), as confirmed by the occurrence of fluid inclusions. Only salammoniac, native sulfur and mascagnite (where crystallized as a monocrystalline phase) were formed directly from a gas phase. The coal-waste heap shows great variations in mineral assemblages among sampling sites, which must be related to variations in waste composition and in conditions at the level at which the elements are released and where mineral formation takes place.
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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 | 0.002 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".