Sazhinite-(La), Na<sub>3</sub>LaSi<sub>6</sub>O<sub>15</sub>(H<sub>2</sub>O)<sub>2</sub>, a new mineral from the Aris phonolite, Namibia: Description and crystal structure
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Bibliographic record
Abstract
Abstract Sazhinite-(La) is a new mineral from the Aris phonolite, Windhoek, Namibia. It occurs in vesicles within the phonolite, together with other species crystallized from late-stage hydrothermal fluids: natrolite, aegirine, microcline, apophyllite, sphalerite, analcime, fluorite, villiaumite, hydroxylapatite, galena, makatite, quartz, eudialyte, kanemite, tuperssuatsiaite and korobitsynite. Sazhinite-(La) forms small euhedral crystals up to 1 mm long and 0.4 mm wide, elongated along [001] and flattened on (010), exhibiting the forms {h0l} , {100} and {001}. It has good cleavage parallel to {010} and {001}. Twinning was not observed. Crystals are brittle with a Mohs hardness of 3, creamy white with a white streak, vitreous to pearly lustre, and translucent to transparent. In plane-polarized light, crystals are colourless with a = Z, b = Y, c = X. It is biaxial positive with α = 1.524, β = 1.528, γ = 1.544, all ±0.002, 2V z (obs) = 46(1)°, and 2V z (calc.) = 53.6°. Sazhmite-(La) is orthorhombic Pmm 2, a = 7.415(2), b = 15.515(3), c = 7.164(1) Å, and V = 824.2 Å 3 . One crystal was studied by X-ray diffraction, electron microprobe and secondary ion mass spectrometry (SIMS) microanalysis, leading to the average composition (Na 2.87 K 0.02 Sr 0.01 ) Σ2.90 [La 0.41 Ce 0.35 Pr 0.02 Nd 0.04 (Sm,Gd,Dy,Er,Yb) Σ0.01 Th 0.09 U 0.01 Y 0.01 Zr 0.01 Ca 0.08 Li 0.01 ] Σ1.04 (S1 5.87 S 0.06 B 0.01 ) (O 14.86 F 0.14 ).(H 2 O) 2 . Weighted full-matrix least-squares refinement on 3369 reflections yielded R all = 3.8%. The structure is built of corrugated [Si 6 O 15 ] 6- layers linked by [7]-coordinated REE and R 4+ cations. This framework leaves channels that contain three [5]- and [6]-coordinated Na cations per formula unit that compensate for the residual charge on the silicate layers. The SIMS analyses confirm a Na content of 3 atoms per formula unit, leading to an ideal formula of Na 3 LaSi 6 O 15 (H 2 O) 2 . The third Na atom is bonded to H 2 O groups and therefore the total content of both Na and H 2 O may be reduced to 2 and 1 per formula, respectively. The depletion in Na allows for the entrance of high-charge cations such as Th 4+ .
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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) | 0.003 | 0.002 |
| Meta-epidemiology (broad) | 0.003 | 0.001 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.001 | 0.002 |
| Scholarly communication | 0.002 | 0.002 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.002 | 0.002 |
| 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