From structure topology to chemical composition. XXIII. Revision of the crystal structure and chemical formula of zvyaginite, Na<sub>2</sub>ZnTiNb<sub>2</sub>(Si<sub>2</sub>O<sub>7</sub>)<sub>2</sub>O<sub>2</sub>(OH)<sub>2</sub>(H<sub>2</sub>O)<sub>4</sub>, a seidozerite-supergroup mineral from the Lovozero alkaline massif, Kola peninsula, Russia
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Bibliographic record
Abstract
Abstract The crystal structure and chemical formula of zvyaginite, ideally Na 2 ZnTiNb 2 (Si 2 O 7 ) 2 O 2 (OH) 2 (H 2 O) 4 , a lamprophyllite-group mineral of the seidozerite supergroup from the type locality, Mt. Malyi Punkaruaiv, Lovozero alkaline massif, Kola Peninsula, Russia have been revised. The crystal structurewas refined with a new origin in space group C1, a = 10.769(2), b = 14.276(3), c = 12.101(2) Å, α = 105.45(3), β = 95.17(3), γ = 90.04(3)°, V = 1785.3(3.2) Å3, R1 = 9.23%. The electron-microprobe analysis gave the following empirical formula [calculated on 22 (O + F)]: (Na 0.75 Ca 0.09 K 0.04 □ 1.12 )Σ2 (Na 1.12 Zn 0.88 Mn 0.17 Fe 2+ 0.04 □ 0.79 ) Σ3 (Nb 1.68 Ti 1.25 Al 0.07 )Σ3 (Si 4.03 O 14 )O 2 [(OH) 1.11 F 0.89 ]Σ2(H 2 O) 4 , Z = 4. Electron-diffraction patterns have prominent streaking along c* and HRTEM images show an intergrowth of crystalline zvyaginite with two distinct phases, both of which are partially amorphous. The crystal structure of zvyaginite is an array of TS (Titanium-Silicate) blocks connected via hydrogen bonds between H 2 O groups. The TS block consists of HOH sheets (H = heteropolyhedral, O = octahedral) parallel to (001). In the O sheet, the [6]MO(1,4,5) sites are occupied mainly by Ti, Zn and Na and the [6] M O (2,3) sites are occupied by Na at less than 50%. In the H sheet, the [6] MH(1,2) sites are occupied mainly by Nb and the [8] AP(1) and [8] AP(2) sites are occupied mainly by Na and □. The MH and AP polyhedra and Si 2 O 7 groups constitute the H sheet. The ideal structural formula is Na□Nb 2 NaZn□Ti(Si 2 O 7 )2O 2 (OH) 2 (H 2 O)4. Zvyaginite is a Zn-bearing and Na-poor analogue of epistolite, ideally (Na□)Nb 2 Na 3 Ti(Si 2 O 7 ) 2 O 2 (OH) 2 (H 2 O) 4 . Epistolite and zvyaginite are related by the following substitution in the O sheet of the TS-block: (Naþ 2 )epi↔Zn 2+ zvy +□zvy. The doubling of the t1 and t2 translations of zvyaginite relative to those of epistolite is due to the order of Zn and Na along a (t1) and b (t2) in the O sheet of zvyaginite.
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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 | 0.003 | 0.003 |
| Meta-epidemiology (narrow) | 0.008 | 0.007 |
| Meta-epidemiology (broad) | 0.010 | 0.004 |
| Bibliometrics | 0.002 | 0.004 |
| Science and technology studies | 0.004 | 0.008 |
| Scholarly communication | 0.004 | 0.004 |
| Open science | 0.009 | 0.008 |
| Research integrity | 0.007 | 0.008 |
| Insufficient payload (model declined to judge) | 0.000 | 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 it