THE CRYSTAL STRUCTURE AND CRYSTAL CHEMISTRY OF MANITOBAITE, IDEALLY (Na16 )Mn2+ 25Al8(PO4)30, FROM CROSS LAKE, MANITOBA
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Bibliographic record
Abstract
The crystal structures of green (brown) variants of manitobaite, ideally (Na 16 □)Mn 2+ 25 Al 8 (PO 4 ) 30 , monoclinic, Pc , Z = 2: green: a 13.4517(7), b 12.5266(7), c 26.6765(13) A, β 101.582(1)°, V 4403.6(7) A 3 , D calc. 3.642 g/cm 3 ; brown: 13.4499(6), b 12.5046(5), c 26.6148(11) A, β 101.221(1)°, V 4390.7(5)(3) A 3 , D calc. 3.621 g/cm 3 , from pegmatite #22 at Cross Lake, Manitoba, Canada, have been solved by direct methods and refined to R 1 = 5.0 (6.0)% for 22,580 (25,613) unique ( F o > 4σ F ) reflections collected on a Bruker single-crystal P 4 diffractometer equipped with a 4K CCD detector and Mo K α X-radiation. Chemical analysis by electron microprobe plus Fe 3+ determination by Mossbauer spectroscopy gave: green: P 2 O 5 44.19, Al 2 O 3 6.91, Fe 2 O 3 1.73, FeO 6.23, MnO 27.57, ZnO 0.54, MgO 0.73, CaO 1.71, Na 2 O 9.97, sum 99.58 wt%; brown: P 2 O 5 44.42, Al 2 O 3 6.96, Fe 2 O 3 3.54, FeO 4.66, MnO 27.86, ZnO 0.53, MgO 0.81, CaO 1.59, Na 2 O 8.94, sum 99.32 wt%. The resulting empirical formulae are as follows: green: Na 15.55 Ca 1.47 Mg 0.88 Fe 2+ 4.19 Mn 2+ 18.78 Zn 0.32 Al 6.54 Fe 3+ 1.05 P 30.08 O 120 ; brown: Na 13.90 Ca 1.37 Mg 0.97 Fe 2+ 3.12 Mn 2+ 18.92 Zn 0.31 Al 6.58 Fe 3+ 2.09 P 30.15 O 120 . The general formula of manitobaite is (Na 16 □)(Mn 2+ ,Fe 2+ ,Mg,Zn,Ca) 25 (Al,Fe 3+ ) 8 (PO 4 ) 30 , and the end-member formula is (Na 16 □)Mn 2+ 25 Al 8 (PO 4 ) 30 . There are 80 cation sites and 120 anion sites in the structure. There are 30 tetrahedrally coordinated sites occupied by P, 33 octahedrally coordinated sites occupied by Mn 2+ , Fe 2+ , Al, Fe 3+ plus minor Mg and Zn, and 17 sites occupied predominantly by Na with coordination numbers from [5] to [8]. Manitobaite is an ordered superstructure of the alluaudite structure. In particular, there are eight octahedrally coordinated sites occupied predominantly by Al, emphasizing the key role of Al in producing superstructures in these minerals.
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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 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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 it