Rinkite-(Y), Na<sub>2</sub>Ca<sub>4</sub>YTi(Si<sub>2</sub>O<sub>7</sub>)<sub>2</sub>OF<sub>3</sub>, a seidozerite-supergroup TS-block mineral from the Darai-Pioz alkaline massif, Tien-Shan mountains, Tajikistan: Description and crystal structure
Bibliographic record
Abstract
Abstract Rinkite-(Y), ideally Na2Ca4YTi(Si2O7)2OF3, is a new rinkite-group (seidozerite-supergroup) TS-block mineral from the Darai-Pioz alkaline massif, Tian-Shan mountains, Tajikistan. The mineral is of hydrothermal origin. It occurs as aggregates (up to 1.5 cm long) of acicular crystals 0.1–1.0 mm thick, and as separate elongated columnar, flattened-prismatic crystals up to 1 cm long with rectangular or rhombic sections up to 0.5 mm across. Associated minerals are quartz, aegirine, microcline, neptunite, pectolite, calcite, eudialyte-group minerals, fluorite, titanite, turkestanite, kupletskite, galena, albite and pyrochlore-group minerals. Crystals are transparent and colourless to occasionally white, with a vitreous lustre. Rinkite-(Y) has a white streak, uneven, conchoidal fracture and does not fluoresce under a cathode or ultraviolet light. Cleavage is very good on {100}, no parting was observed, Mohs hardness is ~5, and it is brittle, Dmeas. = 3.44(2) g/cm3, Dcalc. = 3.475 g/cm3. It is biaxial (+) with refractive indices (λ = 590 nm) α = 1.662(2), β = 1.666(2), γ = 1.685(5); 2Vmeas. = 50(3) and 2Vcalc. = 49.7°. It is nonpleochroic. Rinkite-(Y) is monoclinic, space group P21/c, a = 7.3934(5), b = 5.6347(4), c = 18.713(1) Å, β = 101.415(2)° and V = 764.2(2) Å3. The six strongest reflections in the X-ray powder diffraction data [d(Å), I, (hkl)] are: 3.057, 100, (006, $\bar{2}$ 12, 210); 2.688, 28, (016); 9.18, 24, (002); 2.929, 17, ( $\bar{2}$ 13, 211); 3.559, 15, (104, 014) and 2.783, 14, (021). The empirical formula calculated on 18 (O + F) is Na2.11(Ca3.74Sr0.03Mn0.03)Σ3.80(Y0.50Nd0.16Ce0.16Gd0.07Dy0.06Sm0.05Pr0.03La0.03 ${\rm U}_{0.01}^{{\rm 4 + }} {\rm )}_{\Sigma 1.07}{\rm (T}{\rm i}_{0.85}{\rm N}{\rm b}_{0.17}{\rm W}^{6+}_{0.01}{\rm T}{\rm a}_{0.01}{\rm )}_{\Sigma 1.04}\left( {{\rm S}{\rm i}_{4.03}{\rm O}_{14}} \right){\rm O}_{1.40}{\rm F}_{2.60}$ with Z = 2. The ideal formula is Na2Ca4YTi(Si2O7)2OF3. The crystal structure was refined on a twinned crystal to R1 = 4.59% on the basis of 1489 unique reflections (F > 4σF) and is a framework of TS (Titanium-Silicate) blocks. The TS block consists of HOH sheets (H – heteropolyhedral, O – octahedral) parallel to (100). In the O sheet, the Ti-dominant [6]MO1 site ideally gives 1 Ti apfu. The [8]MO2 and [6]MO3 sites are ideally occupied by Na and (NaCa) apfu. In the H sheet, the [7]MH site is occupied by Ca1.13Y0.50REE0.37, (REE = rare-earth element), ideally (CaY), H–φ> = 2.415 Å and the [7]AP site is occupied by Ca1.81REE0.19, ideally Ca2, P –φ> = 2.458 Å. The MH + AP sites ideally give (Ca3Y) apfu. The MH and A P polyhedra and Si2O7 groups constitute the H sheet. Linkage of H and O sheets via common vertices of MH and A P polyhedra and Si2O7 groups with MO1–3 polyhedra results in a TS block. The TS block in rinkite-(Y) exhibits linkage 1 and stereochemistry typical for the rinkite group (Ti = 1 apfu) of the seidozerite supergroup. For rinkite-(Y), the ideal structural formula of the form A P 2MH2MO4(Si2O7)2 $ \left( {{\rm X}_{\rm M}^{\rm O} } \right)_2\left( {{\rm X}_{\rm A}^{\rm O} } \right)_2{\rm is }\;\left( {{\rm C}{\rm a}_3{\rm Y}} \right){\rm Na}\left( {{\rm NaCa}} \right){\rm Ti}\left( {{\rm S}{\rm i}_2{\rm O}_7} \right)_2\left( {{\rm OF}} \right){\rm F}_2 $ with Z = 2. The mineral is named rinkite-(Y) as it is structurally identical to rinkite-(Ce) and Y is the dominant rare-earth element.
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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 | 0.000 | 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) | 0.002 | 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 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".