Dellaventuraite, NaNa2(MgMn23+Ti4+Li)Si8O22O2, a new anhydrous amphibole from the Kajlidongri Manganese Mine, Jhabua District, Madhya Pradesh, India
Bibliographic record
Abstract
Dellaventuraite is a new amphibole species from the Kajlidongri manganese mine, Jhabua District, Madhya Pradesh, India. It occurs with leakeite, kornite, albite, braunite, and bixbyite associated with cross-cutting epigenetic veins that have reacted with regionally metamorphosed rocks containing Mn-rich minerals (braunite, bixbyite, jacobsite, spessartine) to produce Mn-rich amphiboles, Mnrich pyroxenes, Mn-rich mica, piemontite, and manganophyllite. Dellaventuraite occurs as anhedral grains, the color of which varies from pink to red, depending on Mn content. It is brittle, H = 5, Dcalc = 3.184 g/cm 3 , has a pale pink streak, vitreous luster, and does notfluoresce in ultraviolet light; it has perfect cleavage on {110} and conchoidal fracture. In transmitted plane-polarized light, dellaventuraite is strongly pleochroic, X = pale mauve-brown, Y ~ Z = dark red-brown; Y ^ a = 20° (in β obtuse), Z = b, with absorption X < Y ~ Z. It is biaxial positive, η α = 1.688 ± 0.003, η β = 1.692 ± 0.005, η γ = 1.721 ± 0.003, 2V (obs) = 49 ± 3°, 2V (calc) = 41°. Dellaventuraite is monoclinic, space group C2/m, a = 9.808(1), b = 17.840(2), c = 5.2848(5) Å, γ = 104.653(1)°, V = 894.6(2) Å 3 , Z = 2. The strongest ten X-ray diffraction lines in the powder pattern are [d(I,hkl)]: 2.697(10,151), 2.542(9,.202), 3.127(8,310), 3.378(7,131), 2.154(7,261), 1.434 (7,.661), 4.450(6,021), 8.459(5,110), 2.727(5,.331), 2.328(5,.351). Analysis by a combination of electron microprobe, SIMS and crystal-structure refinement gives SiO 2 = 54.22, Al 2 O 3 = 0.81, TiO 2 = 5.45, Fe 2 O 3 = 6.44, Mn 2 O 3 = 7.57, ZnO = 0.12, NiO = 0.16, MgO = 8.26, Li 2 O = 1.53, CaO = 1.85, Na 2 O = 8.12, K 2 O = 2.12, H 2 O = 0.80, Cr, V, F, Cl not detected, sum 97.41 wt%. The formula unit, calculated on the basis of 24(O,OH,F) is (K 0.40 Na 0.61 )(Na 1.71 Ca 0.29 ) (Mg 1.81 Zn 0.01 Ni 0.02 -Li 0.90 Fe 3+ 0.71 Mn 3+ 0.85Ti 4+ 0.60Al 0.10 )(Si 7.96 Al 0.04 )O 22 [(OH) 0.80 O 1.20 ]; the ideal end-member composition NaNa 2 (MgMn 3+ 2 LiTi0 4+ )Si 8 O 22 O 2 . The crystal structure of dellaventuraite was refined to an R index of 3.8% using MoKα X-ray intensity data. The M1 site is occupied by Ti 4+ , Mn 4+ , and Mg in approximately equal amounts, the M2 site is occupied primarily by Mg and Fe 3+ , and M3 is occupied by Li with minor Mg and Mn 2+ . Local bond-valence considerations suggest that O 2- at O3 is linked to Ti 4+ Mg or Mn 3+ Mn 3+ at the adjacent M1 sites, and that OH at O 3 is linked to MgMg at the adjacent M1 sites.
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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 | 0.001 | 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) | 0.001 | 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".