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Record W2060687203 · doi:10.2113/gscanmin.42.3.797

THE CRYSTAL CHEMISTRY OF EPISTOLITE

2004· article· en· W2060687203 on OpenAlex

Why this work is in the frame

A frame that forgets how it found something cannot be audited. These are the routes that admitted this work.

affAt least one author lists a Canadian institution in the pinned OpenAlex snapshot.
fundA Canadian funder is recorded on the work.
venuePublished in a venue whose home country is Canada.

Bibliographic record

VenueThe Canadian Mineralogist · 2004
Typearticle
Languageen
FieldMaterials Science
TopicCrystal Structures and Properties
Canadian institutionsUniversity of Manitoba
FundersNatural Sciences and Engineering Research Council of Canada
KeywordsCrystal chemistryChemistryCrystal (programming language)CrystallographyCrystal structureComputer science

Abstract

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The crystal structure of epistolite, ideally Na4 Nb2 Ti4+ (Si2O7)2 O2 (OH)2 (H2O)4, a 5.460(1), b 7.170(1), c 12.041(2) Å, 103.63(3), 96.01(3), 89.98(3)°, V 455.4(5) Å3, space group P¯1, Z = 1, Dcalc 2.987 g.cm–3 from the Ilímaussaq alkaline complex, South Greenland, has been solved by direct methods and refined to R1 9.8 % on the basis of 1986 unique reflections |Fo ≥ 4F | collected on a Bruker P4 diffractometer with a CCD 1K Smart detector and MoK radiation. An electron-microprobe analysis gave (wt.%): SiO2 29.59, Nb2O5 31.43, TiO2 10.24, MnO 0.34, Fe2O3 0.35, Ta2O5 0.28, Na2O 14.45, CaO 1.89 K2O 0.27, P2O5 0.36, F 1.32, H2O (calculated from structure refinement) 10.46, total 100.43. The empirical formula is (Na3.79 Ca0.27 Mn0.04)4.06 (Nb1.92 Ti4+0.04 Fe3+0.04)2.00 Ti4+ (Si2O7)2 O2 (OH1.44 F0.56) (H2O), calculated on the basis of 4 Si (apfu). In the crystal structure, there are two tetrahedrally coordinated sites occupied by Si, with a grand <Si–O> distance of 1.617 Å. The (SiO4) tetrahedra link together to form [Si2O7] groups. There are two octahedrally coordinated M sites. The M(1) site is occupied prima-rily by Nb with minor amounts of Fe3+ and Ti4+, with <M(1)–O, H2O> = 2.01 Å. The M(2) site is occupied solely by Ti4+, with <M(2)–O,OH> = 1.962 Å. There are three A sites, occupied primarily by Na: the A(1) and A(2) sites are octahedrally coordinated, with <A(1,2)–O,OH> = 2.39 Å, and the A(3) site is [8]-coordinated, with <A(3)–O,OH,H2O> = 2.57 Å. The A(1) site is occupied by Na, the A(2) site is occupied 92 % by Na, and the A(3) site is approximately half-occupied by Na: 0.87 Na + 0.82 + 0.27 Ca + 0.04 Mn2+ apfu. The M(2) and A(1,2) octahedra each share six common edges to form a close-packed sheet. This sheet of

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Full frame distilled prediction

Teacher imitation

Not 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.

metaresearch head score (Codex)0.000
metaresearch head score (Gemma)0.000
Version: codex-gemma-dda1882f352aValidation status: machine_predicted_unvalidated
Candidate categoriesnone
Consensus categoriesnone
DomainCandidate signal: none · Consensus signal: none
Study designCandidate signal: Bench or experimental · Consensus signal: none
GenreCandidate signal: Empirical · Consensus signal: Empirical
Teacher disagreement score0.709
Threshold uncertainty score0.561

Codex and Gemma teacher scores by category

CategoryCodexGemma
Metaresearch0.0000.000
Meta-epidemiology (narrow)0.0000.000
Meta-epidemiology (broad)0.0000.000
Bibliometrics0.0000.000
Science and technology studies0.0000.001
Scholarly communication0.0000.000
Open science0.0000.000
Research integrity0.0000.000
Insufficient payload (model declined to judge)0.0000.000

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.

Opus teacher head0.011
GPT teacher head0.205
Teacher spread0.194 · how far apart the two teachers sit on this one work
Validation statusscore_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from it