Noonkanbahite, BaKNaTi<sub>2</sub>(Si<sub>4</sub>O<sub>12</sub>)O<sub>2</sub>, a new mineral species: description and crystal structure
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Bibliographic record
Abstract
Abstract Noonkanbahite, ideally BaKNaTi 2 (Si 4 O 12 )O 2 , is described as a new mineral species. At Liley [Löhley], Eifel Mountains, Germany (the holotype locality), it occurs as sprays of prismatic crystals (up to 8 mm) or single prismatic crystals (up to 4 mm) on walls of cavities in alkaline igneous rocks. At Murun, Siberia, Russia, noonkanbahite forms coarse lamellar crystals up to 0.05 cm × 0.7 cm × 1.5 cm embedded in kalsilite syenite. Noonkanbahite is brittle, H = 6, D obs. = 3.39(1), D calc. = 3.49 g/cm 3 , has a vitreous lustre and does not fluoresce in ultraviolet light. It has poor cleavage on {010} and {100} and weak parting on {011}. Noonkanbahite is biaxial positive with 2V obs. = 75(2)°, 2V calc. = 72.7(9)°, α 1.730(5), β 1.740(5) and γ 1.765(5), dispersion is medium, r < v . In transmitted plane-polarized light, noonkanbahite is strongly pleochroic, with X colourless, Y yellowish, Z straw-yellow; X = a , Y = b , Z = c . Noonkanbahite is orthorhombic, space group Imma , a = 8.0884(4), b = 10.4970(5), c = 13.9372(6) Å, V = 1183.3(1) Å 3 , Z = 4. The strongest ten X-ray diffraction lines in the powder pattern [ d in Å ( I )( hkl )] are: 2.907(100)(222), 8.353(50)(001), 3.196(50)(220), 2.097(50)(242), 2.241(40)(215), 2.179(40)(035), 3.377(30)(031), 2.694(30)(015), 2.304(30)(233), and 1.564(30)(064). Electron microprobe analysis gives SiO 2 37.82, TiO 2 15.54, ZrO 2 0.42, Nb 2 O 5 3.18, Al 2 O 3 0.17, Fe 2 O 3 (recalculated from FeO) 5.63, MnO 0.32, MgO 0.53, BaO 20.60, CaO 1.36, K 2 O 5.32, Na 2 O 6.14, F 0.78, H 2 O 0.58, sum 98.39 wt.%, (H 2 O determined by SIMS). The formula unit, calculated on the basis of 14 anions (O+OH+F), is (Ba 0.85 K 0.13 ) Σ 0.98 (K 0.59 Na 0.26 Ca 0.15 ) Σ1.00 Na(Ti 1.23 Fe 0.45 3+ Nb 0.15 Mg 0.08 Mn 0.03 Zr 0.02 Al 0.01 ) Σ 1.97 (Si 3.99 Al 0.01 O 12 )(O 1.33 OH 0.41 F 0.26 ) Σ 2.00 , Z = 4. The crystal structure was refined to R 1 = 2.8% for 970 unique ( F 0 > 4σ F ) reflections collected on a Bruker single-crystal P 4 diffractometer with a CCD detector and M o K α X-radiation. The crystal structure of noonkanbahite is isostructural with that of batisite, ideally BaNa 2 Ti 2 (Si 4 O 12 )O 2 , and scherbakovite, ideally K 2 NaTi 2 (Si 4 O 12 )O(OH). There are two octahedrally coordinated sites, M (1) and M (2), occupied by (Ti 1.23 Fe 0.45 3+ Nb 0.15 Mg 0.08 Mn 0.03 Zr 0.02 Al 0.01 ), ideally Ti 2 a.p.f.u. There are three interstitial A sites, [9] A (1), [8] A (2) and [6] A (3), occupied by Ba, K and Na, respectively. Si tetrahedra and M octahedra form a framework with interstitial cages occupied by Ba, K and Na atoms at the A sites. Noonkanbahite, BaKNaTi 2 (Si 4 O 12 )O 2 , is a K analogue of batisite, BaNa 2 Ti 2 (Si 4 O 12 )O 2 , and a Ba analogue of shcherbakovite, K 2 NaTi 2 (Si 4 O 12 )O(OH).
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.002 | 0.001 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.002 |
| 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