This research field deals with all kinds of hydrothermal fluids (sedimentary brines, magmatic fluids, metamorphic fluids…), which participate in ore forming processes. We focus in particular on orogenic gold deposits, gold-rich volcanic-hosted massive sulfide deposits, carbonatite-hosted HFSE-REE deposits and hydrothermal vein type and MVT deposits with base metal ores. The base for studying the various deposit types is a full fluid characterisation by the use of microthermometry, Microraman spectroscopy, crush leach analysis and LA-ICPMS, where the first three methods are applied in house. Our goal is to decipher the physico chemical conditions of formation of a particular deposit or deposit type. Based on the applied methods, we are able to distinguish, source, sink and pathway processes leading to ore deposit formation. A detailed characterisation of the participating fluids is critical to build a mineral system and to predict new ore deposits.