Ore variability is a big challenge for mineral processing operations, especially in the flotation of complex polymetallic sulphide ores. Processing and blending strategies are determined mostly based on chemical and mineralogical characterization. However, surface characteristics of sulphide minerals is an equally important parameter affecting flotation performance. Changes in surface characteristics of sulphide minerals are usually studied at laboratory scale by using sophisticated equipment, such as ToFSIMs, XPS, etc. In this paper, use of Oxidation Index methodology based on the EDTA extraction technique was evaluated for determination of the presence of secondary copper minerals and surface oxidation of sulphide minerals using a low grade VMS ore deposit from Turkey. These two surface chemistry parameters are known to influence flotation performance significantly, particularly in the copper flotation stage. Therefore, ore variability across the entire ore deposit was evaluated using the relationship between Oxidation Index and flotation performance. The results showed that this methodology can potentially be used as a practical and cost effective method for mapping an ore body regarding variations in surface chemistry of sulphide minerals, prediction of flotation recoveries and selectivity.