V-RICH MINERALS IN CONTACT-METAMORPHOSED SILURIAN SEDEX DEPOSITS IN THE POBLET AREA, SOUTHWESTERN CATALONIA, SPAIN
The Lower Llandoverian metasedimentary rocks of the Prades Mountains, southwestern Catalonia, Spain, consist of interstratified anorthite-rich beds, chert beds, phosphate beds, sulfide-rich black shale (with mainly pyrrhotite and minor chalcopyrite), massive sulfide lenses and calc-silicate beds. These metasedimentary rocks are anomalously enriched in V and Cr, and have disseminated minerals of precious metals: mainly sperrylite and palladian lollingite. The V- and Cr-rich associations are the result of an isochemical metamorphism of V- and Cr-rich protoliths. The contact metamorphism of V-rich shale produced metapelitic hornfels with V-rich aluminosilicates and V–Cr oxides. The occurrence of V oxides in apparent equilibrium with V-rich silicates suggests a limit for the V and Cr contents in these aluminosilicates at the conditions of thermal metamorphism. On the other hand, metamorphism of anorthite- and V-,Cr-rich sedimentary rocks produced V- and Cr-rich silicates, such as goldmanite, V-rich amphiboles, V-rich titanite and V-rich allanite.
PGE-BEARING MINERALS IN SILURIAN SEDEX DEPOSITS IN THE POBLET AREA, SOUTHWESTERN CATALONIA, SPAIN
The Lower Llandoverian metasedimentary series of the Prades Mountains, in southwestern Catalonia, Spain, consists of interbedded massive feldspar beds, composed of almost pure anorthite, with chert, phosphate beds, sulfide-rich black shale, massive sulfides and minor calc-silicate beds. The sulfides mainly consist of pyrrhotite with minor chalcopyrite. The metasedimentary rocks are anomalously V- and Cr-rich and contain disseminated minerals bearing precious metals, e.g. , sperrylite and palladian lollingite. On the basis of the geological setting of ore formation and the textural relationships among the minerals, a sedex model is proposed for the primary origin of these deposits and occurrences. However, textural patterns and mineral compositions were modified during several episodes. Firstly, Hercynian deformation and associated regional low-grade metamorphism produced cleavage and small-scale veining in the primary associations. Later, contact metamorphism related to Late Hercynian intrusions annealed the mineral associations. A sulfidation stage of mineralization caused replacement of Pd-bearing lollingite by arsenopyrite. During this process, the arsenopyrite structure was unable to accommodate such high Pd contents and, consequently, Pd was precipitated as PdAs 2 and scarce small grains of native Pd, disseminated along the lollingite – arsenopyrite contact, in association with argentian gold, and tellurides and selenides of Au, Ag, Bi and Pb.
Athenian Democracy at War
Classical Athens perfected direct democracy. The plays of this ancient Greek state are still staged today. These achievements are rightly revered. Less well known is the other side of this success story. Democratic Athens completely transformed warfare and became a superpower. The Athenian armed forces were unmatched in size and professionalism. This book explores the major reasons behind this military success. It shows how democracy helped the Athenians to be better soldiers. For the first time David M. Pritchard studies, together, all four branches of the armed forces. He focuses on the background of those who fought Athens' wars and on what they thought about doing so. His book reveals the common practices that Athens used right across the armed forces and shows how Athens' pro-war culture had a big impact on civilian life. The book puts the study of Athenian democracy at war on an entirely new footing.