Davidlloydite, ideally Zn<sub>3</sub>(AsO<sub>4</sub>)<sub>2</sub>(H<sub>2</sub>O)<sub>4</sub>, a new arsenate mineral from the Tsumeb mine, Otjikoto (Oshikoto) region, Namibia: description and crystal structure
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
Abstract Davidlloydite, ideally Zn 3 (AsO 4 ) 2 (H 2 O) 4 , is a new supergene mineral from the Tsumeb mine, Otjikoto (Oshikoto) region, Namibia. It occurs as elongated prisms (∼10:1 length-to-width ratio) that are flattened on {010}, and up to 100 × 20 × 10 μm in size. The crystals occur as aggregates (up to 500 μm across) of subparallel to slightly diverging prisms lying partly on and partly embedded in fine-grained calcioandyrobertsite. Crystals are prismatic along [001] and flattened on {010}, and show the forms {010} dominant and {100} subsidiary. Davidlloydite is colourless with a white streak and a vitreous lustre; it does not fluoresce under ultraviolet light. The cleavage is distinct on {010}, and no parting or twinning was observed. The Mohs hardness is 3 – 4. Davidlloydite is brittle with an irregular to hackly fracture. The calculated density is 3.661 g cm –3 . Optical properties were measured with a Bloss spindle stage for the wavelength 590 nm using a gel filter. The indices of refraction are α = 1.671, β = 1.687, γ = 1.695, all ±0.002; the calculated birefringence is 0.024; 2V obs = 65.4(6)°, 2V calc = 70°; the dispersion is r < v, weak; pleochroism was not observed. Davidlloydite is triclinic, space group P1, with a = 5.9756(4), b = 7.6002(5), c = 5.4471(4) Å, α = 84.2892(9), β = 90.4920(9), γ = 87.9958(9)°, V = 245.99(5) Å 3 , Z = 1 and a:b:c = 0.7861:1:0.7167. The seven strongest lines in the X-ray powder diffraction pattern [listed as d (Å), I , ( hkl )] are as follows: 4.620, 100, (011, 10); 7.526, 71, (010); 2.974, 49, (200, 0 1); 3.253, 40, (021, 120); 2.701, 39, ( 10, 002, 1); 5.409, 37, (001); 2.810, 37, (210). Chemical analysis by electron microprobe gave As 2 O 5 43.03, ZnO 37.95, CuO 5.65, H 2 O(calc) 13.27, sum 99.90 wt.%. The H 2 O content and the valence state of As were determined by crystal structure analysis. On the basis of 12 anions with H 2 O = 4 a.p.f.u., the empirical formula is (Zn 2.53 Cu 0.39 )Σ2.92As 2.03 O 8 (H 2 O) 4 . The crystal structure of davidlloydite was solved by direct methods and refined to an R 1 index of 1.51% based on 1422 unique observed reflections collected on a three-circle rotating-anode (Mo K α radiation) diffractometer equipped with multilayer optics and an APEX-II detector. In the structure of davidlloydite, sheets of corner-sharing (As 5+ O 4 ) and (ZnO 4 ) tetrahedra are linked by ZnO 2 (H 2 O) 4 octahedra. The structure is related to that of parahopeite.
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 | 0.002 | 0.001 |
| Meta-epidemiology (narrow) | 0.003 | 0.002 |
| Meta-epidemiology (broad) | 0.003 | 0.001 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.002 | 0.002 |
| Scholarly communication | 0.002 | 0.003 |
| Open science | 0.002 | 0.002 |
| Research integrity | 0.002 | 0.002 |
| Insufficient payload (model declined to judge) | 0.000 | 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 it