THE CRYSTAL CHEMISTRY OF MALINKOITE, NaBSiO4, AND LISITSYNITE, KBSi2O6, FROM THE KHIBINA LOVOZERO COMPLEX, KOLA PENINSULA, RUSSIA
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Bibliographic record
Abstract
The crystal structure of malinkoite, NaBSiO 4 , a 13.8964(4) A, c 7.7001(2) A, P 6 3 , Z = 18, D x = 2.922 g cm −3 , from the Khibina–Lovozero complex, Kola peninsula, Russia, has been solved by direct methods and refined to an R index of 3.8% using 2094 unique observed (| F o | > 4σ F ) reflections collected with a single-crystal diffractometer fitted with a CCD detector and Mo K α X-radiation. Malinkoite is a framework borosilicate with a structure consisting of six-membered rings of regularly alternating (SiO 4 ) and (BO 4 ) tetrahedra, and Na located in the large channels extending along [001]. There are three unique Si sites, each occupied by Si and each coordinated by four O atoms in a tetrahedral arrangement, with Si –O> distances of 1.625, 1.622 and 1.622 A, respectively. There are three unique B sites, each occupied by B and each coordinated by four O atoms in a tetrahedral arrangement, with B –O> distances of 1.476, 1.476 and 1.473 A, respectively. There are five unique Na sites, each completely occupied by Na. Three of the Na sites are [9]-coordinated, with Na –O> distances of 2.626, 2.642 and 2.630 A, respectively; the remaining two Na sites are [6]-coordinated, with Na –O> distances of 2.444 and 2.440 A, respectively. The (SiO 4 ) and (BO 4 ) tetrahedra link to form six-membered rings of two different configurations based on the following sequences of up ( U ) and down ( D ) linkages: UDUDUD and UUDUDD in the ratio of 1:2. Nine-coordinated Na polyhedra are located in big cages formed by stacking of UDUDUD rings. Stacking of UUDUDD rings produces smaller cages occupied by [6]-coordinated Na. In accord with the ratio of two types of rings, there are twelve Na octahedra and six [9]-coordinated Na polyhedra per unit cell in malinkoite. The framework topology is related to that of beryllonite NaBePO 4 . In the crystal structure of lisitsynite, KBSi 2 O 6 , four-membered rings consist of two (SiO 4 ) and two (BO 4 ) tetrahedra, and are linked into zig-zag chains (puckered ladders) along [001]. There are two types of chemically distinct six- and eight-membered rings: (4Si + 2B) and (5Si + B); (5Si + 3B) and (6Si + 2B). Two different pairs of six-membered and eight-membered rings, (4Si + 2B) and (5Si + 3B), and (5Si + B) and (6Si + 2B), respectively, form sheets on (100) and (010). Stacking of sheets and zig-zag chains gives rise to a three-dimensional framework. There are one-dimensional seven-ring channels along the c direction. Lisitsynite, KBSi 2 O 6 , and synthetic “boroleucite”, K(Si 2 B)O 6 , may be regarded as polymorphs with different patterns of Si–B order.
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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 | 0.000 | 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 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 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 it