In recent years, satellite image and other data provided by the terrestrial component of remote sensing technology have been used for detecting hydrothermal alteration minerals and regional geology mappings. Existing rock detection methods and algorithms in remote sensing can only be used to determine main rock groups such as ultramafic, granitoid, metamorphic and sedimentary. The use of new remote sensing methods in the determination of subgroups of these rocks (i.e. ultramafic rocks consist of harzburgite, dunite and lherzolite) is important for geological mapping. In particular, the mapping of dunite is necessary for the exploration of chromite deposits. In this study, it was aimed to determine the spectral behaviour of dunite in a new band ratio and to adopt a new hybrid band combination for geological mapping and exploration of new chromite mineralization areas. Due to the presence of the complex units it holds, it is composed mainly of ultramafic rocks, and Eskikarahisar Region, Sivas City (Turkey), where it is located on the South of Sivas, was selected as study area. Ultramafic rock samples were collected in the study area. To determine the types and mineral contents of the samples, petrographic investigations of the samples were conducted for identifying the samples that contain dunite. Spectral measurements of the representative dunite samples were taken to combine the averages of spectral signatures. After merging spectral signatures and the ASTER SWIR band regions, ASTER SWIR bands that could be used for rationing were determined for adopting a new ASTER band rationed image and band with enhanced images data. This article focuses on the adopting a hybrid combination with gamma transform applied, which contains the rationed image and enhanced ASTER SWIR components, leading to effective mapping of dunite rocks exposed on the study area.