The Eymir (Yozgat-Sorgun, Turkey) manganese deposit occurs within radiolarite cherts of the lower Cretaceous ophiolite complex. The mineralization was observed banded and lenticular forms. The geochemical characteristics of the Eymir deposit was studied by means of major oxide, trace and rare earth element (REE) contents and the origin of mineralization was discussed. The correlation coefficients indicated the presence of strong positive relations between major oxides and various trace elements (Al(2)O(3)-Fe(2)O(3): r=0.75; Al(2)O(3)-CaO: r=0.79; Al(2)O(3)-TiO(2): r=0.80; Al(2)O(3)-Zr: r=0.66; TiO(2)-Fe(2)O(3): r=0.98; TiO(2)-CaO: r=0.82; TiO(2)-Zr: r=0.85 and Fe(2)O(3)-Zr: r=0.89) and the contribution of mafic terrigenous material to the deposition. In chondrite normalized REE graphics samples were characterized by highly negative and positive Ce anomalies. Europium showed negative anomaly in all samples. The negative Ce anomaly was typical to submarine hydrothermal deposits and positive Ce anomaly was indicative of hydrogenous deposits. The negative Eu anomaly showed contamination from the continental crust and/or sediment contribution via dehydration. Ce values in the Eymir mineralization were computed from the equation of Ce(anom)=lg [3xCe(N)/(2xLa(N)+Nd(N))] and anomalies were found as Ce(anom)<-0.1 in 8 samples and Ce(anom)>-0.1 in 12 samples. These values are indicative of both oxic and anoxic sedimentation conditions. The available data indicated that the Eymir manganese deposit is a hydrothermal-hydrogenous type volcanosedimentary mineralization.