MANGANILVAITE, CaFe2+Fe3+(Mn, Fe2+)(Si2O7)O(OH), A NEW MINERAL OF THE ILVAITE GROUP FROM Pb Zn SKARN DEPOSITS IN THE RHODOPE MOUNTAINS, BULGARIA
Bibliographic record
Abstract
Manganilvaite, CaFe2+Fe3+(Mn,Fe2+)(Si2O7)O(OH), is a new mineral species, the Mn end-member of the ilvaite group of minerals. It was found in the Pb–Zn–(Mn) skarn deposits of the central Rhodope Mountains, Bulgaria, and especially in the Ossikovo and Mogilata deposits (Madan ore district) and the Govedarnika deposit (Laki district). In the marble-hosted distal skarn-type orebodies, it is closely associated with Mn-rich clinopyroxene (hedenbergite–johannsenite) ± rhodonite, and with the products of their retrograde alteration (manganoan amphiboles and chlorites, bustamite, manganoan carbonates, quartz). The mineral is black, with a vitreous luster, brittle, with a distinct cleavage. It has Mohs hardness of 5½–6 and a micro-indentation hardness (VHN100) of 868 kg/mm2. The measured density Dx is 3.92 g/cm3. In reflected light, it is opaque with moderate pleochroism, from bluish gray to grayish brown, strongly anisotropic in grayish blue to pale reddish brown colors and with red internal reflections. It is homogeneous in BSE images and in thin sections under the IR microscope, where it is transparent. The reflectance is low, in the range 8.3–5.7% for Rmin (// c) and 10.0–9.3% for Rmax (// a). In some cases, well-shaped dipyramidal crystals occur, with a prismatic habit along c and forms r{011}, m{110}, s{210} and o{111}. The average results of 62 and 17 electron-microprobe analyses of manganilvaite from Ossikovo and Govedarnika, respectively, are (in wt.%): MgO 0.48, 0.45; Al2O3 0.20, 0.34; SiO2 29.65, 29.48; CaO 12.62, 13.06; TiO2 0.02, 0.04; MnO 11.99, 13.54; FeO 40.93, 39.31, (H2O 2.21), total 98.10, 98.43. The MnO content varies in the ranges 9.02–14.96 and 12.57–14.86%, respectively, the amount of Mn attaining 0.85 apfu. The mineral is of ilvaite-type structure, monoclinic, P21/a, with cell-edge parameters a 13.0250(7), b 8.8514(5), c 5.8486(3) A, β90.167(1)°, V 674.28 A3, Z = 4, as determined by composite X-ray and neutron powder-diffraction studies (see the companion paper). Manganese occupies the M2 octahedral position together with some Fe2+. Ilvaite and manganilvaite form a continuous solid-solution series, and gradations between them can be observed even in a single crystal. The strongest eight lines of the X-ray powder-diffraction pattern [d in A(I)(hkl)] are: 2.875(85)(130), 2.848(90)(401), 2.718(100)(112), 2.687(70)(230), 2.442(33)(231), 2.180(48)(140,402), 2.111(47)(322,412), and 1.475(48)(060,252). As a product of retrograde alteration of the early-skarn pyroxenes, manganilvaite indicates evolution of the hydrothermal process from reduction to more oxidized and hydrated environment. The mineral name recalls its composition and relation to ilvaite.
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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 | 0.000 |
| 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 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".