THE CRYSTAL CHEMISTRY OF THE SCAPOLITE-GROUP MINERALS. I. CRYSTAL STRUCTURE AND LONG-RANGE ORDER
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.
Bibliographic record
Abstract
Scapolite-group minerals are a group of rock-forming framework aluminosilicates common in a wide variety of igneous and metamorphic rocks. They have the general formula M 4 [ T 12 O 24 ] A , where M represents Na, K, Ca, Sr, Ba and Fe 2+ , T stands for Si, Al, (Fe 3+ ), and A represents Cl, (CO 3 ), (SO 4 ). They constitute a non-binary solid-solution series involving the end members marialite (Na 4 [Al 3 Si 9 O 24 ] Cl, Ma ) and meionite (Ca 4 [Al 6 Si 6 O 24 ] CO 3 , Me ). The crystal structures of eighteen scapolite-group minerals from Me 4.9 to Me 92.8 [ Me = 100 ∑ M 2+ /∑( M 2+ + M + )] have been refined with Mo K α X-radiation. The crystals, a 12.045–12.208, c 7.564–7.586 A, V 1099.7–1130.1 A 3 , I 4/ m or P 4 2 / n , Z = 2, were analyzed with an electron microprobe subsequently to collection of the X-ray intensity data. There are subtle differences between the behavior of the distinct T tetrahedra in the I 4/ m and P 4 2 / n structures. For Si and Al, determinative curves for the assignment of site populations from T –O> distances were developed for each T site in each structure type, and T -site populations were assigned from these curves. In I 4/ m marialite, there is no Al at the T (1) site. In P 4 2 / n scapolite, Al is strongly ordered at T (2), and Si is strongly ordered at T (3), but this order is never complete. The A -site cation (Na, Ca, K) is [8]-coordinated in end-member marialite and is (on average) [8.5]-coordinated in end-member meionite. Each ( M ϕ n ) polyhedron shares two edges with adjacent ( M ϕ n ) polyhedra, forming a three-dimensional framework that interpenetrates the [ T 12 O 24 ] silicate framework. In (CO 3 )-bearing structures, the model proposed by previous workers, four (CO 3 ) groups arranged about the 4 axis ( I 4/ m ) or 4 axis ( P 4 2 / m ), is consistent across the series from marialite to meionite. Any (SO 4 ) present is disordered by rotation of 90° about the central 4-fold axis; in I 4/ m structures, each arrangement is 50% occupied, whereas in P 4 2 / n structures, the occupancies of the two arrangements are not required to be equal.
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.
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 | 0.001 | 0.002 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 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 it