THE CRYSTAL STRUCTURE OF TVALCHRELIDZEITE, Hg3SbAsS3, AND A REVISION OF ITS CHEMICAL FORMULA
Bibliographic record
Abstract
We have determined the crystal structure of tvalchrelidzeite, Hg3SbAsS3, for the Þ rst time with single-crystal X-ray diffrac-tion. It is monoclinic, with space group P21/n and unit-cell parameters a 11.5526(4), b 4.3852(1), c 15.6373(5) Å, 91.845(2)°, V 791.79(5) Å3. There are eight symmetrically distinct sites in the structure, three occupied by Hg, one by Sb, one by As, and three by S. There is no disorder between Sb and As. Each Sb is surrounded by six S2 anions, with three at distances shorter than 2.51 Å and three at distances longer than 3.20 Å. In contrast, each As is coordinated by six Hg2+ cations, with three at distances shorter than 2.51 Å and three at distances longer than 3.31 Å. All three independent Hg ions are situated in considerably distorted octahedral sites, with two opposite bonds (one HgS and one HgAs) shorter than 2.51 Å and four equatorial bonds longer than 2.98 Å. The structure of tvalchrelidzeite can be viewed as a sequence of sheets parallel to (101). These sheets are composed of [Hg6Sb2As2S6] ribbon-like units (extending along the b axis) linked together by the short Hg1As bonds (2.494 Å). The linkage between sheets is achieved through the weak HgS (>3.0 Å) and SbS (>3.2 Å) bonds, accounting for the observed perfect cleavage in one direction. Tvalchrelidzeite represents one of very few sulfosalt minerals that contain both Sb and As, with the latter behaving as an anion.
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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 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 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; 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".