New compositional data concerning Au-Ag alloys from the northern part of Roşia Montană deposit, Metaliferi Mountains, Romania
Résumé
This paper presents the results of the new investigations by optical microscopy, scanning electron microscopy (SEM) and electron-probe micro-analysis (EPMA) performed on samples collected from Orlea adit from Roşia Montană Au-Ag deposit, Romania. Based on composition, three types of Au-Ag alloy were described. At Roşia Montană, galena, pyrite, chalcopyrite and sphalerite are intimately associated with gold, electrum and tellurium-bearing minerals. At Roşia Montană, the precipitation of Au-Ag alloy with variable composition can be assigned to compositional changes of the parent hydrothermal solutions during deposition due to boiling, fluid dilution and cooling.