Agakhanovite-(Y), ideally (YCa) 2KBe3Si12O30, a new milarite-group mineral from the Heftetjern pegmatite, Tordal, Southern Norway: Description and crystal structure
Bibliographic record
Abstract
Agakhanovite-(Y), ideally (YCa)⃞2KBe 3 Si 12 O 30 , is a new milarite-group mineral from the Heftetjern pegmatite, Tørdal, southern Norway. Crystals are prismatic along [001], and show the forms {100} and {100}. Agakhanovite-(Y) is colorless with a white streak and a vitreous luster, and does not fluoresce under ultraviolet light. There is no cleavage or parting, and no twinning was observed. Mohs hardness is 6, and agakhanovite-(Y) is brittle with a conchoidal fracture. The calculated density is 2.672 g/cm 3 . Optical properties were measured with the Bloss spindle stage for the wavelength 590 nm using a gel filter. Agakhanovite-(Y) is uniaxial (-) with indices of refraction w = 1.567, e = 1.564, both ±0.002; the calculated birefringence is 0.003 and it is non-pleochroic. Agakhanovite-(Y) is hexagonal, space group P6/mcc, a = 10.3476(2), c = 13.7610(3) Å, V = 1276.02(9) Å 3 , Z = 2, c:a = 1.330. The seven strongest lines in the X-ray powder-diffraction pattern are as follows: d (Å), I, (hkl): 2.865, 100, (1̅24); 3.287, 96, (1̅31); 4.134, 84, (1̅22); 6.877, 56, (002); 2.986, 43, (030); 4.479, 38, (020); 2.728, 36, (024). Chemical analysis by electron microprobe gave SiO 2 69.56, Al 2 O 3 0.35, Y 2 O 3 9.69, Yb 2 O 3 0.15, FeO 0.02 CaO 5.75, Na 2 O 0.07, K 2 O 4.52, BeO(calc) 7.06, H 2 O(calc) 1.74, sum 98.91 wt%. The H 2 O content was determined by crystal-structure analysis. On the basis of 30 anions, the empirical formula is (Y 0.89 Yb 0.01 Ca 1.06 )S 1.96 (H 2 O) 0.92 Na 0.02 K 1.00 (Be 2.93 Al 0.07 )S 3.00 Si 12.02 O 30 . The crystal structure of agakhanovite-(Y) was refined to an R 1 index of 1.9% based on 660 unique observed reflections collected on a three-circle rotating-anode (MoKa X-radiation) diffractometer equipped with multilayer optics and an APEX-II detector. In the end-member structure of agakhanovite-(Y), the A site is occupied equally by Y and Ca, and the B site is vacant; agakhanovite-(Y) is the Y-analog of oftedalite: ScCa⃞ 2 KBe 3 Si 12 O 30 , and the Y-Ca-Be analog of klöchite, (Fe 2+ Fe 3+ )⃞ 2 KZn 3 Si 12 O 30 .
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
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".