The present thesis deals with the behaviour of different metals in a pyro-metallurgical treatment for jarosite with a special focus on indium and silver. The work starts with a market analysis for indium and silver, which shows that the demand of indium will increase faster than for other metals, like e.g. zinc. The main source for the production of indium is the hydrometallurgical zinc industry. Therefore, it is necessary to increase the recovery rates or treat secondary resources. There is nearly no literature accessible for indium, consequently it was mandatory to do thermodynamically investigations as a preliminary point for the experimental part of the study. The experimental part investigated the behaviour of the metals in different atmospheres and the influence of additives on the volatilization of silver and indium. While it was possible to volatilize 80,8 % of the silver with sodium chloride, it was not possible to evaporate indium in a satisfactory manner.