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Tetrahedrite-(Cu), Cu12Sb4S13, from Bankov near Košice, Slovak Republic: A new member of the tetrahedrite group minerals
Full text linkTetrahedrite-(Cu), Cu12Sb4S13, was approved as a new mineral species from the Bankov magnesite deposit near Koxˇice, Slovak Republic where it occurs as anhedral grains, up to 0.4 mm across, associated with skinnerite, chalcostibite, famatinite, tetrahedrite-(Fe) and zoned aggregates of tennantite-(Cu) to tennantite-(Fe). Tetrahedrite-(Cu) is steel-grey, with metallic luster. Mohs hardness is ca. 31/2 - 4, calculated density is 5.029 g.cm-3. In reflected light, tetrahedrite-(Cu) is isotropic, grey with bluish shade. Reflectance data for the four COM wavelengths in air are [λ (nm): R (%)]: 470: 31.1; 546: 30.1; 589: 29.9; 650: 28.1. The empirical formula, based on electron-microprobe data (mean of 17 spot analyses), is Cu11.42Zn0.26Fe0.19(Sb4.06As0.08)Σ4.14S12.99. The ideal formula is Cu6(Cu4Cu2)Sb4S13, which requires (in wt.%) Cu 45.76, Sb 29.23 and S 25.01, total 100.00. Tetrahedrite-(Cu) is cubic, I 3m, with unit-cell parameters a = 10.3296(15) Å, V = 1102.2(5) å3, Z = 2. Its crystal structure was refined by single-crystal X-ray diffraction data to a final R1= 0.0347 on the basis of 261 unique reflections with Fo> 4σ(Fo) and 22 refined parameters. Tetrahedrite-(Cu) is isotypic with other tetrahedrite-group minerals. Previous findings of tetrahedrite-(Cu) are reported and some nomenclature issues, related to the Fe and Cu oxidation states, are 4 discussed. At the Bankov deposit, tetrahedrite-(Cu) is related to hydrothermal, most probably Alpine, solutions strongly enriched in Cu, Sb and S
Argentotetrahedrite-(Zn), Ag-6(Cu4Zn2)Sb4S13, a new member of the tetrahedrite group
No full textArgentotetrahedrite-(Zn), Ag-6(Cu4Zn2)Sb4S13, has been approved as a new mineral species by the International Mineralogical Association Commission on New Minerals, Nomenclature and Classification (IMA-CNMNC) using samples from Kremnica, Slovak Republic (hereafter KR), and Lengenbach, Switzerland (LE). Additionally, it was also identified at the small deposit of Zvestov (Stfibrnice), Czech Republic (ZV). At the Slovak locality, it occurs as anhedral grains up to 0.1 mm in size, steel-grey in colour, with a metallic lustre, in association with 'argentotennantite-(Fe)' and tiny chalcopyrite grains in quartz gangue. At Lengenbach, it was found as domains of tristetrahedral crystal of tetrahedrite-(Zn), up to 1 mm in size, associated with dolomite. At Zvestov, it occurs as irregular aggregates, up to 0.2 mm in size, partly rimmed by kenoargentotetrahedrite-(Fe). Argentotetrahedrite-(Zn) is isotropic, grey in colour, with blue-greenish tints. Reflectance data for COM wavelengths in air (KR sample) are [lambda (nm), R (%)]: 470, 30.1; 546, 29.8; 589, 29.8; and 650, 28.3. Chemical formulae of the samples studied, recalculated, on the basis of Sigma Me = 16 apfu (atoms per formula unit), are: (Ag3.27Cu2.69)Es-96[Cu-4.00(Zn1.69Fe0.23Cu0.05Cd0.02Hg0.01)Sigma(2.00)](Sb3.86As0.17)(Sigma 4.03)S-12.73 (KR), (Ag3.17Cu2.79)(Sigma 5.96)]Cu-4.00(Zn1.55Cd0.23Fe0.16Cu0.05Hg0.01)(Sigma 2.00)](Sb(3.71)AS(0.32))(Sigma 4.03)S-12.77 (LE) and (Ag3.27Cu2.67)(Sigma 5.94)[Cu-0.04(Zn1.39Fe0.50Cu0.03Hg0.00](Sigma 2.00)](Sb4.03As0.04)Sigma S-4.07(13.05 )(ZV). Argentotetrahedrite-(Zn) is cubic, 1 (4) over bar 3m, with a = 10.5505(10) angstrom, V = 1174.4(3) angstrom(3) and Z = 2 (KR); a = 105155(13) angstrom and V= 1162.8(4) angstrom(3) (LE); and a= 10.5663(12) angstrom and V= 1179.7 angstrom(3) (ZV). The crystal structure of argentotetrahedrite-(Zn) has been refined by single-crystal X-ray diffraction data to a final R-1 = 0.035 on the basis of 327 unique reflections with F-o > 4 sigma(F-o) and 22 refined parameters (sample KR). Argentotetrahedrite-(Zn) is isotypic with other members of the tetrahedrite group. The structural relationship between argentotetrahedrite-(Zn) and other members of the freibergite series are discussed and previous findings of this species are briefly reviewed
Ferriandrosite-(Ce), a new member of the epidote supergroup from Betliar, Slovakia
No full textA new member of the epidote supergroup, ferriandrosite-(Ce), ideally MnCeFe3+AlMn2+(Si2O7)(SiO4)O(OH), was found at the Július manganese ore occurrence near Betliar, Rožnava Co., Košice Region, Slovakia. It occurs as subhedral grains and polycrystalline aggregates, up to 0.3 mm in size, enclosed in pyroxmangite. Other associated minerals are spessartine, rhodochrosite, quartz, baryte and pyrosmalite-(Mn). Ferriandrosite-(Ce) is dark brown, with a light brown streak and vitreous lustre. The Mohs hardness is about 6 1/2 to 7, tenacity is brittle without any observable cleavage or fracture. The calculated density is 4.321 g·cm-3. Ferriandrosite-(Ce) is optically biaxial (+), with weak pleochroism, high surface relief and the mean calculated refractive index is 1.832. The empirical structural formula of ferriandrosite-(Ce), based on 13 anions per formula unit, is A1(Mn2+0.63Ca0.35Ce0.02)S1.00A2(Ce0.53La0.27Nd0.14Pr0.05REE*0.01)S1.00M1(Fe3+0.41Al0.12V3+0.01Mg0.40Ti0.05)S0.99M2Al1.00M3(Mn2+0.75Fe2+0.22Mg0.03)S1.00T1-3Si3.00O11O4(O0.67F0.33)(OH), where REE* are minor REE. Ferriandrosite-(Ce) is monoclinic, space group P21/m, a = 8.8483(4) Å, b = 5.7307(3) Å c = 10.0314(5) Å, ß = 113.3659(15)°, V = 466.95(4) Å3and Z = 2. The crystal structure of ferriandrosite-(Ce) was refined to a final R1= 0.0210 for 1910 reflections with Fo> 4s(Fo) and 127 refined parameters. Structural features of ferriandrosite-(Ce) are discussed and compared with other members of the androsite-series
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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