Sveinbergeite, Ca(Fe<sup>2+</sup><sub>6</sub> Fe<sup>3+</sup>)Ti<sub>2</sub>(Si<sub>4</sub>O<sub>12</sub>)<sub>2</sub>O<sub>2</sub>(OH)<sub>5</sub>(H<sub>2</sub>O)<sub>4</sub>, a new astrophyllite-group mineral from the Larvik Plutonic Complex, Oslo Region, Norway: description and crystal structure
Bibliographic record
Abstract
Abstract Sveinbergeite, Ca(Fe 2+ 6 Fe 3+ )Ti 2 (Si 4 O 12 ) 2 O 2 (OH) 5 (H 2 O) 4 , is a new astrophyllite-group mineral discovered in a syenite pegmatite at Buer on the Vesteroya peninsula, Sandefjord, Oslo Region, Norway. The mineral occurs in pegmatite cavities as 0.01—0.05 mm thick lamellar (0.2—0.5×5—10 mm) crystals forming rosette-like divergent groups and spherical aggregates, which are covered by brown coatings of iron (and possibly manganese) oxides, associated with magnesiokatophorite, aegirine, microcline, albite. calcite, fluorapatite, molybdenite, galena and a hochelagaite-like mineral. Crystals of sveinbergeite are deep green with a pale green streak and a vitreous and pearly lustre. Sveinbergeite has perfect cleavage on ﹛001﹜ and a Mohs hardness of 3. Its calculated density is 3.152 g/cm 3 . It is biaxial positive with α 1.745(2), β 1.746(2), γ 1.753(2), 2V(meas.) = 20(3)°. The mineral is pleochroic according to the scheme Z > X ∽ Y : Z is deep green, X and Y are brownish green. Orientation is as follows: X ┴ L (001), Y ᶺ b = 12°, Z = a, elongation positive. Sveinbergeite is triclinic, space group P1̄, a = 5.329(4), b = 11.803(8), c = 11.822(8) Å; α = 101.140(8)°, β = 98.224(8)°, γ = 102.442(8)°; V = 699.0(8) Å 3 ; Z = 1. The nine strongest lines in the X-ray powder diffraction pattern [d in Å(I)(hkl)] are: 11.395(100)(001,010). 2.880(38)(004), 2.640(31)(2̄10,l̄41), 1.643(24)(07̄1,072), 2.492(20)(2l̄l), 1.616(15)(070), 1.573(14)(3̄2̄2), 2.270(13)(1̄3̄4) and 2.757(12)(1̄40,1̄3̄2). Chemical analysis by electron microprobe gave Nb 2 O 5 0.55, TiO 2 10.76, ZrO 2 0.48, SiO 2 34.41, A1 2 O 3 0.34, Fe 2 O 3 5.57, FeO 29.39, MnO 1.27, CaO 3.87, MgO 0.52, K 2 O 0.49, Na 2 O 0.27, F 0.24, H 2 O 8.05, O=F -0.10, sum 96.11 wt.%, the amount of H 2 O was determined from structure refinement, and the valence state of Fe was calculated from structure refinement in accord with Mossbauer spectroscopy. The empirical formula, calculated on the basis of eight (Si + Al) p.f.u., is (Ca 0.95 Na 0.12 K 0.14 ) Σ1.21 (Fe 2+ 5.65 Fe 3+ 0.93 Mn 0.25 Mg 0.18 ) Σ7.01 (Ti 1.86 Nb 0.06 Zr 0.05 Fe 3+ ) Σ2 (Si 7091 Al 0.09 ) Σ8 O 34.61 H 12.34 F 0.17 , Z = 1. The infrared spectrum of the mineral contains the following absorption frequencies: 3588, ∽3398 (broad), ∽3204 (broad), 1628, 1069, 1009, 942, 702, 655 and 560 cm –1 . The crystal structure of the mineral was solved by direct methods and refined to an R 1 index of 21.81%. The main structural unit in the sveinbergeite structure is an HOH layer which is topologically identical to that in the astrophyllite structure. Sveinbergeite differs from all other minerals of the astrophyllite group in the composition and topology of the interstitial A and B sites and linkage of adjacent HOH layers. The mineral is named in honour of Svein Arne Berge (b. 1949), a noted Norwegian amateur mineralogist and collector who was the first to observe and record this mineral from its type locality as a potential new species.
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How this classification was reachedexpand
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 | 0.005 | 0.003 |
| Meta-epidemiology (narrow) | 0.013 | 0.011 |
| Meta-epidemiology (broad) | 0.011 | 0.005 |
| Bibliometrics | 0.003 | 0.007 |
| Science and technology studies | 0.006 | 0.007 |
| Scholarly communication | 0.006 | 0.007 |
| Open science | 0.009 | 0.007 |
| Research integrity | 0.007 | 0.010 |
| Insufficient payload (model declined to judge) | 0.001 | 0.003 |
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; both teacher heads agree on what is shown here.
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".