Byzantievite, Ba<sub>5</sub>(Ca,<i>REE</i>,Y)<sub>22</sub>(Ti,Nb)<sub>18</sub>(SiO<sub>4</sub>)<sub>4</sub>[(PO<sub>4</sub>),(SiO<sub>4</sub>)]<sub>4</sub> (BO<sub>3</sub>)<sub>9</sub>O<sub>21</sub>[(OH),F]<sub>43</sub>(H<sub>2</sub>O)<sub>1.5</sub>: the crystal structure and crystal chemistry of the only known mineral with the oxyanions (BO<sub>3</sub>), (SiO<sub>4</sub>) and (PO<sub>4</sub>)
Bibliographic record
Abstract
Abstract The crystal structure of byzantievite, Ba 5 (Ca, REE ,Y) 22 (Ti,Nb) 18 (SiO 4 ) 4 [(PO 4 ),(SiO 4 )] 4 (BO 3 ) 9 O 21 [(OH),F] 43 (H 2 O) 1.5 , a new mineral from the moraine of the Dara-i-Pioz glacier, the Alai mountain ridge, Tien-Shan Mountains, northern Tajikistan, was solved by direct methods and refined to R 1 = 13.14% based on 3794 observed [ F o >4σ| F |] unique reflections measured with Mo- K α X-radiation on a Bruker P 4 diffractometer equipped with a CCD detector. Byzantievite is hexagonal, space group R 3, a = 9.1202(2) Å, c = 102.145(5) Å, V = 7358.0(5) Å 3 , Z = 3, D calc. = 4.151 g cm –3 . The empirical formula (electron microprobe analysis) is Ba 5.05 [(Ca 8.99 Sr 0.96 Fe 2+ 0.42 Na 0.20 ) Σ10.57 (Ce 3.46 La 1.54 Nd 1.20 Pr 0.30 Sm 0.26 Dy 0.41 Gd 0.32 Th 0.39 U 4+ 0.17 ) Σ8.05 Y 3.53 ] Σ22.15 (Ti 12.31 Nb 5.30 ) Σ17.61 (SiO 4 ) 4.65 (PO 4 ) 3.12 (BO 3 ) 8.89 O 22.16 (OH) 38.21 F 4.89 (H 2 O) 1.5 , Z = 3, calculated on the basis of 124.5 (O + F) a.p.f.u. The H 2 O and OH contents were calculated from structure refinement (F + OH = 43 a.p.f.u.; H 2 O = 1.5 a.p.f.u..), and B was determined by SIMS. The crystal structure is a framework of Ti-Ba-Ca- REE -dominant polyhedra and SiO 4 , PO 4 and BO 3 groups. In the crystal structure, there are 50 cation sites, 23 of which are fully occupied and 27 partly occupied: six of the 27 partly-occupied sites are >50% occupied, 21 <50% occupied. The crystal structure of byzantievite is an intercalation of three components, one fully ordered with 100% occupancy of cation sites, and two partly ordered with cation-site occupancies of 67% and 17% respectively. Byzantievite is the only known mineral that contains all three of the oxyanions (BO 3 ), (SiO 4 ) and (PO 4 ) as essential components.
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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 | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 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".