The Structure and Thermochemistry of Three Fe-Mg Chlorites
Bibliographic record
Abstract
Abstract Chlorites are petrogenetically important minerals, exercise controls on petroleum reservoir qualities, are common in alteration zones during hydrothermal ore mineralization, and may form during carbon sequestration in sedimentary formations. Chlorite thermochemistry and structure have been investigated, in the present study, to facilitate an improved understanding of chlorite equilibria. Three natural II b chlorites were studied by powder diffraction and calorimetric methods (low-temperature relaxation calorimetry using a Physical Properties Measurement System [PPMS] and differential scanning calorimetry [DSC]). The samples include a low-Fe clinochlore [Mg-Chl] and two Fe-rich chlorites from Windsor [Fe-Chl(W)] and Michigan [Fe-Chl(M)]. The structure of each chlorite was refined in the ideal C 2/ m symmetry using Rietveld techniques. Lattice parameters for the Windsor chlorite are a = 5.3786(6) Å, b = 9.3176(9) Å, c = 14.2187(6) Å, β = 96.98(10)°. The Michigan chlorite returned a = 5.3897(3) Å, b = 9.3300(3) Å, c = 14.2376(2) Å, β = 97.043(5)° whereas the low-Fe clinochlore yielded a = 5.3301(3) Å, b = 9.2231(8) Å, c = 14.2912(4) Å, β= 97.03(10)°. Heat capacities ( C p ) for the three natural chlorites were measured using both PPMS (2–303 K) and DSC (282–564 K). Employing a combination of Debye-Einstein-Schottky functions, the lattice dynamics component of the C p at lower temperature was evaluated allowing a separation of the magnetic spin ordering component of C p from the lattice vibrational part. For Mg-Chl, Fe-Chl(W), and Fe-Chl(M), the polynomials defining the temperature dependencies of the heat capacities between 280 and 570 K are: C p = 1185.44(±68.93) − 9753.21(±186.85) T −0.5 − 1.9094(±1.0288)·10 7 T −2 + 3.3013(±1.5363)·10 9 T −3 C p = 1006.06(±48.46) − 4134.83 (±1515.16) T −0.5 − 40.0949(±6.9413)·10 6 T −2 + 5.9386(±1.0287)·10 9 T −3 and C p = 1268.60(±67.16) − 11983.09(±2107.07) T −0.5 − 7.6037(±9.6417)·10 6 T −2 + 1.5398(±1.4187)·10 9 T −3 , respectively. Standard state molar thermodynamic functions, C P , S T , ( H T − H 0 )/ T , and φ were evaluated for the samples. S 298.15 for Fe-Chl(W), Mg-Chl, and Fe-Chl(M) were found to be 499.14 ± 3.40, 437.81 ± 3.00 and 515.06 ± 3.60 J mol -1 K -1 , respectively, whereas S ° for Fe-Chl(W) and Mg-Chl were determined to be 578.24 ± 3.76 and 503.21 ± 3.60 J mol −1 K −1 , −1
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How this classification was reachedexpand
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 | 0.000 | 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) | 0.000 | 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 itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, 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".