Mineralogy of metallic phases in sulphide mattes from primary lead smelting

The mattes resulting from lead smelting have been studied in order to determine the distribution of heavy metals and metalloids in primary phases. The chemical analysis (EPMA) revealed the presence of various metals (Pb, Sb, Cu), sulphides (galena, wurtzite, pyrrhotite, bornite, digenite, cubanite), arsenides (koutekite, löllingite) and other complex intermetallic compounds. Extreme saturation of the initial matte melt in heavy metals and metalloids as well as a relatively rapid cooling regime are responsible for numerous elemental substitutions in the crystal structures of all the involved phases. To cite this article: V. Ettler, Z. Johan, C. R. Geoscience 335 (2003).     

Apports des phyllosilicates dans la différenciation entre altération hypogène et altération supergène dans le basalte triasique du Moyen Atlas (Maroc)Contribution of phyllosilicates to distinguish between hypogene alteration and weathering in Triassic basalt from Middle Atlas (Morocco)

Triassic basalt of the Middle Atlas has been subject to metamorphic transformation then weathering. Occurrence in both metabasalt and saprolite of ubiquitous clay minerals, such as smectite and mixed layers chlorite–smectite, makes it difficult to distinguish between the two alteration facies and explains the interest of complementary sources of information. In the Bhallil weathering profile, petrographical and mineralogical analyses of primary igneous minerals and their alteration products coupled with Fe oxidation state determination in clay fractions allow to identify three alteration facies: (i) metamorphic basalt, where iron occurs mainly as the ferrous form; (ii) the lower part of saprolite, where iron is partially oxidized to its ferric form; (iii) the upper part of saprolite, where iron is completely oxidized. To cite this article: A. Dekayir et al., C. R. Geoscience 334 (2002) 877–884.