Davidbrownite-(NH<sub>4</sub>), (NH<sub>4</sub>,K)<sub>5</sub>(V<sup>4+</sup>O)<sub>2</sub>(C<sub>2</sub>O<sub>4</sub>)[PO<sub>2.75</sub>(OH)<sub>1.25</sub>]<sub>4</sub>·3H<sub>2</sub>O, a new phosphate–oxalate mineral from the Rowley mine, Arizona, USA
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Bibliographic record
Abstract
Abstract Davidbrownite-(NH 4 ), (NH 4 ,K) 5 (V 4+ O) 2 (C 2 O 4 )[PO 2.75 (OH) 1.25 ] 4 ·3H 2 O, is a new mineral species from the Rowley mine, Maricopa County, Arizona, USA. It occurs in an unusual bat-guano-related, post-mining assemblage of phases that include a variety of vanadates, phosphates, oxalates and chlorides, some containing NH 4 + . Other secondary minerals found in association with davidbrownite-(NH 4 ) are antipinite, fluorite, mimetite, mottramite, quartz, rowleyite, salammoniac, struvite, vanadinite, willemite and wulfenite. Crystals of davidbrownite-(NH 4 ) are light green–blue needles or narrow blades up to ~0.2 mm long. The streak is white, the lustre is vitreous, Mohs hardness is ca . 2, tenacity is brittle and fracture is splintery. There are two good cleavages in the [010] zone, probably {100} and {001}. The measured density is 2.12(2) g cm –3 . Davidbrownite-(NH 4 ) is optically biaxial (+) with α = 1.540(2), β = 1.550(5) and γ = 1.582(2) (white light); 2V = 58.5(5)°; moderate r > v dispersion; and orientation Z = b and Y ≈ a . Pleochroism: X = pale blue, Y = nearly colourless, Z = light blue; and Y < X < Z . Electron microprobe analysis gave the empirical formula [(NH 4 ) 3.11 K 1.73 Na 0.09 ] Σ4.93 [(V 4+ 1.92 Mg 0.01 Al 0.02 ) Σ1.95 O 2 ](C 2 O 4 ) [(P 3.94 As 0.12 ) Σ4.06 O 10.94 (OH) 5.06 ]·3H 2 O, with the C and H content provided by the crystal structure. Raman and infrared spectroscopy confirmed the presence of NH 4 and C 2 O 4 . Davidbrownite-(NH 4 ) is monoclinic, P 2 1 / c , with a = 10.356(6), b = 8.923(5), c = 13.486(7) Å, β = 92.618(9)°, V = 1244.9(12) Å 3 and Z = 2. The crystal structure of davidbrownite-(NH 4 ) ( R 1 = 0.0524 for 2062 I o > 2σ I reflections) consists of a chain structural unit with the formula {(V 4+ O) 2 (C 2 O 4 )[PO 2.75 (OH) 1.25 ] 4 } 5– , and a disordered interstitial complex containing five large monovalent cations (NH 4 + and K + ) and three H 2 O groups pfu. Strong hydrogen bonds form links within and between the chains.
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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 | 0.010 | 0.006 |
| Meta-epidemiology (narrow) | 0.018 | 0.016 |
| Meta-epidemiology (broad) | 0.017 | 0.009 |
| Bibliometrics | 0.005 | 0.013 |
| Science and technology studies | 0.007 | 0.009 |
| Scholarly communication | 0.009 | 0.010 |
| Open science | 0.015 | 0.011 |
| Research integrity | 0.011 | 0.015 |
| Insufficient payload (model declined to judge) | 0.001 | 0.023 |
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