FENCOOPERITE, Ba6Fe3+3Si8O23(CO3)2Cl3{middle dot}H2O, A NEW MINERAL SPECIES FROM TRUMBULL PEAK, MARIPOSA COUNTY, CALIFORNIA
Bibliographic record
Abstract
Fencooperite, a new mineral species having the ideal formula Ba 6 Fe 3+ 3 Si 8 O 23 (CO 3 ) 2 Cl 3 ·H 2 O, is trigonal, P 3 m 1, with unit-cell parameters refined from powder data: a 10.727(5), c 7.085(3) A, V 706.1(5) A 3 , c / a 0.6605, Z = 1. The strongest seven lines of the X-ray powder-diffraction pattern [ d in A ( I )( hkl )] are: 3.892(100)(201), 3.148(40)(211), 2.820(90)(202), 2.685(80)(220), 2.208(40)(401), 2.136(40)(222) and 1.705(35)(421). The mineral occurs as a dominant phase within black aggregates 2 mm across in barium-silicate-rich lenses at Trumbull Peak, Mariposa County, California. It is a primary phase, formed after barite, in an aggregate assemblage that includes alforsite, barite, celsian, gillespite, quartz, pyrrhotite and sanbornite. Additional minerals found within the lenses are anandite, benitoite, bigcreekite, fresnoite, kinoshitalite, krauskopfite, macdonaldite, pellyite, titantaramellite, walstromite, witherite, biotite, diopside, fluorapatite, pentlandite, schorl, vesuvianite and three undefined species. Individual grains of fencooperite are anhedral to somewhat rounded to occasionally platy, are jet black to a dirty grey-brown (on very thin edges), do not exceed 100 μm in size, and have an uneven to subconchoidal fracture. Neither morphological forms nor twinning were observed. The streak is greyish black, tenacity is brittle, luster is vitreous to adamantine, and diaphaneity, opaque to translucent (on thin edges). There is no obvious cleavage; D (calc.) 4.338 (for the ideal formula), 4.212 g/cm 3 (for the empirical formula). It is nonfluorescent in ultraviolet light; H (VHN load 10 g) 269 to 367, H (Mohs) 4.5 to 5. Fencooperite is uniaxial negative, O 1.723(4), E 1.711(2), very strongly pleochroic from blue-black ( O ) to light greenish grey ( E ); absorption O ≫ E . Averaged results of electron-microprobe analyses yield BaO 50.51, Fe 2 O 3 12.77, MnO 0.15, SiO 2 27.38, Al 2 O 3 1.35, P 2 O 5 0.16, Cl 3.23, CO 2 [4.81], H 2 O [0.98], sum 101.34, less O = Cl −0.73, total [100.61] wt.%. The empirical formula, derived from results of the crystal-structure analysis and electron-microprobe analyses, is Ba 5.89 (Fe 3+ 2.86 Mn 2+ 0.04 ) ∑2.90 (Si 8.14 Al 0.47 P 0.04 ) ∑8.65 O 23.18 (CO 3 ) 1.95 (Cl 1.63 O 1.37 ) ∑3.00 ·0.97 H 2 O, on the basis of O + Cl = 33. The infrared-absorption spectrum shows bands for carbonate and possibly for structural H 2 O. The mineral name honors Joseph Fenimore Cooper, Jr., Santa Cruz, California, in recognition of his substantive contributions to both mineralogy and mineral collecting in the western United States.
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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 | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".