Hydroterskite: A New Mineral Species From the Saint-Amable Sill, Quebec, and A Comparison With Terskite and Elpidite
Bibliographic record
Abstract
Hydroterskite, ideally Na 2 ZrSi 6 O 12 (OH) 6 , is a new mineral species from the Saint-Amable sill at the Demix-Varennes quarry, near Varennes, Quebec, Canada. Hydroterskite crystals are short prismatic in habit, up to 3 mm in width, and bounded by the {100}, {010}, and {001} prisms. The crystals are translucent, pale gray in color, with a white streak and vitreous luster. Hydroterskite is brittle and splintery, with good cleavages on the prismatic planes. It is biaxial negative, α = 1.562 ± 0.002, β = 1.567 ± 0.002, γ = 1.571 ± 0.002, 2 V meas. = 86(3)°, 2 V calc. = 83°. Dispersion could not be observed, and there is no pleochroism. The optical orientation is X = c , Y = b , and Z = a . The average result of three analyses of a single grain (oxide wt.%) gave Na 2 O 7.82, K 2 O 0.07, CaO 0.62, FeO 0.89, MnO 0.71, Al 2 O 3 0.08, La 2 O 3 0.12, Ce 2 O 3 0.24, SiO 2 59.82, HfO 2 0.11, ThO 2 1.15, ZrO 2 15.00, TiO 2 1.15, Nb 2 O 5 1.12, F 0.11, H 2 O (by stoichiometry) 8.79, for a total (−0.05 O=F) of 96.84. Magnesium, Y, Sr, and Cl were sought but not detected. The empirical formula on the basis of 18 anions with 6 OH − is (Na 1.543 K 0.009 Ca 0.068 La 0.005 Ce 0.009 ) ∑1.634 (Zr 0.744 Ti 0.088 Nb 0.052 Th 0.005 Hf 0.003 Fe 0.076 Mg 0.002 Mn 0.061 Al 0.010 ) ∑1.041 Si 6.087 O 12 (OH 5.963 F 0.035 Cl 0.002 ) ∑6 . The structure of hydroterskite is orthorhombic in the centric space group Pnca , with a 13.956(6), b 14.894(7), c 7.441(4) A, V 1546.8(2.0) A 3 , and Z = 4. It has been refined to an R index of 0.036 on the basis of 1080 observed reflections. There are two crystallographically distinct Na sites, both with eight-fold co-ordination: [ Na1 O 6 (OH) 2 ] is a hexagonal dipyramid polyhedron, whereas [ Na2 O 6 (OH) 2 ] is a bifurcated pentagonal dipyramid. The Zr atom is in a regular octahedral coordination. Silicon, in tetrahedral coordination with oxygen, forms spiral chains parallel to the c axis. These chains are cross-linked by edge-sharing [ZrO 6 ] octahedra and [NaO 8 ] polyhedra. All three H atoms were located. The crystal-structure determination of terskite in the literature was most likely incorrectly assigned to an acentric space-group. The hydroterskite crystal structure is compared to the structures of terskite, elpidite, and yusupovite.
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How this classification was reachedexpand
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 | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, 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".