HOGARTHITE, (Na,K)<sub>2</sub>CaTi<sub>2</sub>Si<sub>10</sub>O<sub>26</sub>·8H<sub>2</sub>O, A NEW MEMBER OF THE LEMOYNITE GROUP FROM MONT SAINT-HILAIRE, QUEBEC: CHARACTERIZATION, CRYSTAL-STRUCTURE DETERMINATION, AND ORIGIN
Bibliographic record
Abstract
Hogarthite, (Na,K)2CaTi2Si10O26·8H2O, a new mineral of the lemoynite group, was discovered in vugs within metasomatically altered marble xenoliths in the Poudrette quarry, Mont Saint-Hilaire, La-Vallee-du-Richelieu RCM, Monteregie, Quebec, Canada. Crystals are bladed to blocky, average 0.05 × 0.15 × 2 mm in size, and range in color from tan to white to colorless. The mineral develops in dense, radiating crystal aggregates up to 0.5 × 3 mm in size, and is associated with calcite (several generations), quartz, haineaultite, labuntsovite-Mn, lemoynite, chabazite, and gmelinite-Na. Crystals are elongate along [100], flattened on {010} and are bounded by the forms pinacoid {010} (dominant), pinacoid {100} (minor), and pinacoid {001} (minor). The mineral has a white streak, is non-fluorescent under short-, medium-, and long-wave ultraviolet radiation, is translucent, and has a satiny to silky to subvitreous luster. It has a brittle fracture, a perfect {010} cleavage, a hackly to splintery fracture, an estimated hardness of 4, and D calc = 2.40(1) g/cm3. Hogarthite is biaxial (+) with α 1.567(1), β 1.591(1), and γ 1.618(1) with 2 V meas = 87(1)o and 2 V calc = 88(1)o. The optical orientation is X = b , Y ˄ c = 15o (measured in the obtuse angle β), Z = a . A total of 21 analyses, obtained from seven crystals, gave an average (range) of (wt.%): Na2O 2.37 (1.69–2.92), K2O 2.88 (2.61–3.17), CaO 6.00 (5.40–6.31), TiO2 14.44 (13.70–15.83), ZrO2 1.11 (0.48–1.73), Nb2O5 0.78 (0.42–1.24), SiO2 59.27 (57.32–60.64), H2O 14.10 (calc.), total 100.95. The empirical formula (based on 34 anions) is (Na0.78K0.62□0.51Ca0.09)Σ2.00Ca(Ti1.85Zr0.09Nb0.06)Σ2.00Si10.09O26·8H2O, and the simplified formula is (Na,K)2CaTi2Si10O26·8H2O. The presence of (OH) and H2O were confirmed via refinement of the crystal-structure and data from combined FTIR and Raman spectroscopies. The mineral crystallizes in space group C 2/ m with a 10.1839(5), b 15.8244(6), c 9.1327(7) A, β 104.463(2)o, V 1425.1(1) A3, and Z = 2. The strongest six lines on the X-ray powder diffraction pattern [ d in A (I) ( hkl )] are: 8.835 (85) (001), 7.913 (100) (020), 6.849 (70) (![Formula][1] 11), 4.336 (45) (![Formula][2] 31, ![Formula][3] 12), 3.514 (80) (221), 3.426 (55) (![Formula][4] 22, ![Formula][5] 32). The crystal structure, refined to R = 0.049 for 1335 reflections ( F o > 4σ F o), consists of a silicate component, composed of interconnected, non-planar 10-membered rings, arranged into thick slabs and stacked along [001]. These are interleaved with layers of independent TiO6 octahedra, producing a framework of composition [TiSi5O13]2–. Numerous channels within the framework, notably the continuous ones developed by 10-membered silicate rings, are occupied by Na, Ca, and H2O groups. Hogarthite is considered to be a product of late-stage alkaline fluid enriched in SiO2 and TiO2, and forming under conditions of low P at T < 200 oC, possibly through crystallization of a gel. [1]: /embed/mml-math-1.gif [2]: /embed/mml-math-2.gif [3]: /embed/mml-math-3.gif [4]: /embed/mml-math-4.gif [5]: /embed/mml-math-5.gif
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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 | 0.001 | 0.001 |
| 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) | 0.002 | 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".