Vermicular petalite-orthoclase intergrowths in quartz: A natural occurrence of stuffed quartz and its implications for economic lithium mineralization 
Bibliographic record
Abstract
Peraluminous rare-metal granites from South China constitute the largest, minable hard-rock lithium resources in the world. An ongoing debate is whether the Li in these granites was concentrated to economic grades via igneous processes alone, or whether metasomatic processes played an indispensable role in achieving economic grades. The Yichun deposit is a suitable locality to study lithium mineralization processes; here, a zoned petalite (LiAlSi4O10)-bearing pegmatite sheet was intruded by underlying Li-rich granites, where both the pegmatite and granites have previously been interpreted to have originated from the same magma. Two types of sequentially crystallized quartz are present in the core zone of the pegmatite. An early quartz yields similar δ18O values to magmatic graphic quartz. This early quartz is fractured, free of mineral inclusions, and was crosscut or partially replaced by an inclusion-rich, late quartz, which exhibits comparable δ18O values to magmatic quartz, as opposed to the higher δ18O values of hydrothermal quartz at Yichun. Titanium-in-quartz thermobarometry constrains that both quartz generations were formed at comparable temperatures to the magmatic graphic quartz and share a magmatic origin. The inclusions in the late quartz are a vermicular variety, composed of abundant petalite and lesser orthoclase. Image analysis-based mass balance calculations yield an average of 2,300 ppm Li in the original melt that formed the mineral assemblage in the late quartz. Such a Li abundance is lower than the minimum Li (~5,000 ppm) required for direct crystallization of petalite from a peraluminous melt. The petalite inclusions are, therefore, interpreted as exsolution from a transient, magmatic quartz-petalite solid solution containing ~2,300 ppm Li and ~8,000 ppm Al that chemically resembled the stuffed quartz synthesized from crystallization experiments. To attain ~2,300 ppm Li in the core zone, 90% fractionation of an initial pegmatite melt containing ca. 300 ppm Li is sufficient, and formation of a boundary layer to concentrate Li is not required. The current evidence suggests that up to 1.2 wt% Li in the Yichun granite-pegmatite system resulted from metasomatism that further added Li. Such metasomatic enrichment likely applies to analogous systems in South China.
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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 | 0.000 | 0.001 |
| 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".