HEPHAISTOSITE, TlPb2Cl5, A NEW THALLIUM MINERAL SPECIES FROM LA FOSSA CRATER, VULCANO, AEOLIAN ISLANDS, ITALY
Bibliographic record
Abstract
Hephaistosite, TlPb 2 Cl 5 , a newly discovered species of thallium lead chloride, was found in a high-temperature fumarole (~400°C) at the rim of La Fossa crater, Vulcano Island, Aeolian archipelago, Sicily, Italy. The mineral occurs as aggregates of pale yellow-green crystals tabular on {010} up to 0.1 mm in length on fragments of altered pyroclastic breccia, in association with bismuthinite (Bi 2 S 3 ), cotunnite (PbCl 2 ), challacolloite (KPb 2 Cl 5 ) and pseudocotunnite (K 2 PbCl 4 ). The mineral is monoclinic, space group P 2 1 / c . Cell parameters refined from powder-diffraction data are: a 8.9477(6), b 7.9218(7), c 12.4955(5) A, β 90.092(4)°, V 885.70(7) A 3 , with Z = 4. The strongest six reflections in the X-ray powder-diffraction data [ d (in A)( I )( hkl )] are: 3.696(100)(013), 3.971(83)(020), 2.109(45)(402,215), 2.569(42)(204), 1.848(41)(142,026), and 2.851(38)(213). Crystals of hephaistosite show the forms {010}, {101}, {110}, {100}, {001}, and {011}. Chemical analyses obtained by EDS microprobe gave, on average, in wt.%, Tl 23.78, K 0.01, Pb 51.78, Cl 21.40, Br 1.34, F 0.17, for a total of 98.48, corresponding to an empirical formula (based on 8 apfu ) of Tl 0.94 Pb 2.01 (Cl 4.85 Br 0.14 F 0.07 ) ∑5.06 . Hephaistosite is isostructural with challacolloite; intermediate members of the series between the two species occur in the same fumarole. The calculated density for the synthetic compound (TlPb 2 Cl 5 ) is 5.932 g/cm 3 . The mean index of refraction n , obtained from a natural sample using Brewster angle measurement, is 2.0(1). The structure was refined using two different crystals, with Tl:K atom ratios of 86:14 and 64:36; the final R index is 0.028 and 0.038, respectively. The mineral, approved by the IMA Commission on New Minerals, Nomenclature and Classification (No. 2006–043), is named in honor of the ancient Greek god of fire, Hephaistos (Hephaestus, Hϕαιστος), whose workshops were alleged to be located at Vulcano.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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 source (direct Gemma or distilled Codex), 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".