Lead hydrogen citrate monohydrate, Pb(C<sub>6</sub>H<sub>6</sub>O<sub>7</sub>)·H<sub>2</sub>O, formation during specimen cleaning: a cautionary mineralogical tale
Bibliographic record
Abstract
Abstract Crystal-structure analysis was used to identify crystals of Pb(C 6 H 6 O 7 )·H 2 O on a specimen of hematite pseudomorphous after magnetite from the Payύn Matrύ volcanic field, Mendoza Province, Argentina. The compound is triclinic, P , a = 6.3434(2), b = 6.4566(2), c = 12.0640(9) Å, α = 99.233(7), β = 102.810(7), γ = 101.562(7)° and Z=2. The crystal structure, refined to R 1 = 0.0169 for 2021 reflections [F o >4σ(F)], consists of a zig-zag chain of 9-coordinated Pb 2+ atoms along b . Chains are linked together by citrate molecules to form thick irregular layers in the ab plane. The layers are linked together only by H bonds. The citrate molecule exhibits normal bond lengths and angles. The Pb 2+ atom exhibits markedly lopsided coordination due to the 6s 2 lone-electron-pair effect. The lone electron pairs on alternating sets of adjacent Pb 2+ atoms in the chain point towards one another. The formation of the Pb(C 6 H 6 O 7 )·H 2 O crystals was the result of specimen cleaning in citric acid. The cleaning solution was apparently contaminated through the dissolution of minor associated Pb-bearing species by the citric acid. It is important to be aware of the possibility that micro-crystals may be inadvertently grown on mineral specimens during chemical cleaning, to carefully and critically inspect paragenetic relationships especially when studying mineral specimens that may have been cleaned in chemical agents, and to be particularly aware of health risks when treating Pb-bearing minerals in aqueous citric acid solutions.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.002 | 0.002 |
| Meta-epidemiology (broad) | 0.002 | 0.001 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.002 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.002 | 0.003 |
| Insufficient payload (model declined to judge) | 0.000 | 0.001 |
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; both teacher heads agree on what is shown here.
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".