1,720,967 research outputs found
Una mineralizzazione sintettonica: il giacimento di Valdicastello (Alpi Apuane). Rapporti tra tettonica e minerogenesi in Toscana
No full textI Giacimenti a barite, pirite e ossidi di ferro delle Alpi Apuane. Studio minerogenetico e strutturale. Nuove osservazioni sui giacimenti polimetallici
No full textI giacimenti minerari delle Alpi Apuane e loro correlazioni con l'evoluzione del gruppo montuoso
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Dessauite, (Sr,Pb)(Y,U)(Ti,Fe)20O38, a new mineral of the crichtonite group from Buca della Vena mine, Tuscany, Italy
No full textDessauite, a new mineral in the crichtonite group, occurs within cavities in calcite veins as tabular {001} rhombohedral, black, millimeter-sized crystals at Buca della Vena Mine, Apuan Alps (Tuscany, Italy). It is associated with derbylite, hematite, rutile, karelianite, siderite, and calcite. Dessauite is trigonal, space group R3, with a = 9.197(1) Å, alpha = 68.75(2)°. Optically, dessauite is opaque and shows low bireflectance and very weak pleochroism. Electron microprobe analyses led to the following simplified chemical formula: (Sr,Pb)(Y,U)(Ti,Fe3+)20O38. The crystal structure of dessauite was refined from single-crystal X-ray diffraction data to R = 0.065. Dessauite is isostructural with the others members of the crichtonite group; a peculiar structural feature is the presence of additional, partially occupied octahedral sites. A comparison of the crystal-chemical formulas of all the minerals within the crichtonite group is presented. In view of the structural information, the analytical data have been re-arranged on the basis of the crystal-chemical formula ABC18T2O38, rather than AM21O38
-1982- Geologia della zona del Valico di Correboi (Sardegna centro-orientale). Rilevamento, tettonica, giacimenti minerari
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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
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