Description: The main objective of the work package 2 of the REFLECT project is to characterise relevant fluid properties and their reactions for saline fluids (type C). One of the specific goals was to collect fluid samples from several saline fluids from geothermal sites across Europe, determine their properties, and thus contribute to the Fluid Atlas (WP3). Additionally, the REFLECT team will compare those field data with data from lab experiments performed at near natural conditions. Samples of type C fluids were taken from several sites in Germany, Austria, Belgium and the Netherlands. The samples were analysed for major and minor ions, dissolved gases and isotopes. On 10th of May 2021, two thermal water samples were taken by TNO before and after the heat exchanger at the geothermal site Heemskerk in the Netherlands. The samples sent to Hydroisotop were analysed for their hydrochemical composition, heavy metal and dissolved organic carbon (DOC) content and stable isotopes (18O, 2H, 13C-DIC). It should be noted that the pH measured in the laboratory diverges from previously observed pH values which in the past have not been reported below 5,4. Concentrations of major ions had initially been reported too low but re-measurement of the samples yielded values in ranges that had previously been recorded. However, the concentraton of Lithium is much higher than expected. In order to resolve these uncertainties, the site Heemskerk will be sampled again. The dataset contains analysis results associated with the research project REFLECT. It is a comma separated file (csv) containing the following columns: Location,Country,Description,Laboratory (Lab.),Lab. No.,Sampling date,Spec. electr. conductivity (25 degC) Lab. (muS/cm),pH value Lab.,Temperature Lab. (degC),Alkalinity (pH 4.3) Lab. (mmol/l),Sodium (mg/l),Potassium (mg/l),Calcium (mg/l),Magnesium (mg/l),Ammonium (mg/l),Hydrogen carbonate (mg/l),Chloride (mg/l),Sulphate (mg/l),Nitrate (mg/l),Antimony (mg/l),Barium (mg/l),Fluoride (mg/l),Iodide (mg/l),Lithium (mg/l),Silicon (mg/l),Strontium (mg/l),Aluminium (mg/l),Arsenic (mg/l),Lead (mg/l),Iron total (mg/l),Copper (mg/l),Manganese total (mg/l),Nickel (mg/l),Uranium (mg/l),Zinc (mg/l),DOC (mg/l),Oxygen-18 d18O-H2O (per mille VSMOW),Deuterium d2H-H2O (per mille VSMOW),Deuterium-excess (per mille VSMOW),Carbon-13 d13C-DIC (per mille VPDB). Methods are described in the accompanying deliverable Fluid data of geothermal sites (type C)