Quaternary loess and loess like deposits covered more than 3200 km² of Golestan Province. Mineralogical aspects of loess deposits were studied on collected samples with east-west trend by random method using X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Analysis (EDXA). The results showed the presence of quartz, calcite and clay minerals like illite and chlorite in loess deposits. Based on mineralogical evidences, it could be suggested that dry and cool climate conditions were dominant at the time of loess deposition