FERRO-OBERTIITE, Na Na2 (Fe2+ 3 Fe3+Ti) Si8 O22O2, A NEW MINERAL SPECIES OF THE AMPHIBOLE GROUP FROM COYOTE PEAK, HUMBOLDT COUNTY, CALIFORNIA
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Bibliographic record
Abstract
Ferro-obertiite, Na Na 2 (Fe 2+3 Fe 3+ Ti) Si 8 O 22 O 2 , is a new mineral species of the amphibole group from Coyote Peak, Humboldt County, California, U.S.A., associated with inclusions of lithic-wacke sandstone in an alkali-rich ultramafic diatreme. Ferro-obertiite occurs as euhedral to subhedral crystals up to 1.25 mm across in a matrix of aegirine and feldspar. Crystals are black with a grey streak. Ferro-obertiite is brittle, has a Mohs hardness of 6, and a splintery fracture; it is non-fluorescent, with perfect {110} cleavage, no observable parting, and has a calculated density of 3.330 g cm −3 . In plane-polarized light, it is pleochroic, X dark brown, Y brown, Z dark grey; X ∧ a = 77.3° (in β acute), Y || b , Z ∧ c = 91.2° (in β obtuse). Ferro-obertiite is biaxial negative, α 1.671(1), β 1.674(1), γ 1.675(1); 2 V (obs.) = 60(3)°, 2 V (calc.) = 59.9°. It is monoclinic, space group C 2/ m , a 9.845(4), b 18.018(8), c 5.296(3) A, β 103.86(3)°, V 912.1(4) A 3 , Z = 2. The strongest ten X-ray-diffraction lines in the powder pattern [ d in A( I )( hkl )] are: 2.722(100)(331,151), 8.448(80)(110), 3.407(60)(131, 041), 3.144(50)(201, 310), 2.596(50)(061), 2.533(40)(202), 2.178(30)(261), 4.514(20)(040, 021), 3.283(20)(240) and 2.332(20)(351). Analysis by a combination of electron microprobe and crystal-structure refinement gave SiO 2 52.47, Al 2 O 3 0.09, TiO 2 6.51, Fe 2 O 3 4.54, FeO 18.43, MgO 5.74, MnO 0.15, CaO 0.90, Na 2 O 8.70, K 2 O 1.51, Li 2 O 0.17, F 0.51, H 2 O 0.58, sum 100.09 wt%. The formula unit, calculated on the basis of 24 (O, OH, F), is A (Na 0.72 K 0.29 ) (Na 1.85 Ca 0.15 ) (Mg 1.30 Fe 2+ 2.35 Mn 2+ 0.02 Fe 3+ 0.52 Al 0.01 Ti 0.75 Li 0.10 ) (Si 7.99 Al 0.01 ) O 22 (O 1.16 F 0.25 OH 0.59 ). The crystal-structure refinement shows Ti to be strongly ordered at the M (1) site. Ferro-obertiite, ideally Na Na 2 (Fe 2+ 3 Fe 3+ Ti) Si 8 O 22 O 2 , is related to obertiite, Na Na 2 (Mg 3 Fe 3+ Ti) Si 8 O 22 O 2 , by the substitution Fe 2+ → Mg.
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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 | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.006 | 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 it