The crystal structure of zigrasite, MgZr(PO<sub>4</sub>)<sub>2</sub>(H<sub>2</sub>O)<sub>4</sub>, a heteropolyhedral framework structure
Bibliographic record
Abstract
Abstract The crystal structure of zigrasite, ideally MgZr(PO4)2(H2O)4, a 5.3049(2), b 9.3372(4), c 9.6282(5) Å, α 97.348(1)°, β 91.534(1)°, γ 90.512(4)°, V 472.79(5) Å3, Z = 2, triclinic, P1, Dcalc. 2.66 g.cm–3, from the giant 1972 pocket at Newry, Oxford County, Maine, USA, has been solved and refined to R1 3.75% on the basis of 2623 unique reflections (Fo > 4σF). There are two P sites, each of which is solely occupied by P with distances of 1.532 and 1.533 Å, respectively. There are two Mg sites, both of which are occupied by Mg and are octahedrally coordinated two O anions and four (H2O) groups with distances of 2.064 and 2.075 Å, respectively. There is one Zr site, occupied by Zr and octahedrally coordinated by six O anions with a distance of 2.065 Å . The (ZrO6) octahedron shares corners with six (PO4) tetrahedra, forminga [Zr(PO4)2] sheet parallel to (001). These sheets are stacked in the c direction and linked by (MgO2(H2O)4) octahedra that share O atoms with the (PO4) groups. The structure is formally a heteropolyhedral framework structure, but the linkage is weaker in the c direction, accounting for the marked (001) cleavage.
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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 | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| 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".