Egerci village is located 16 km southwest of Yerkoy (Yozgat) area which has a ferromanganese deposit that formed at the contact between basalt and limestone and shows that a banded stockwork structure occurs occasionally within the limestone. The mineralization consists of pyrolusite, goethite, and ramsdellite, together with a lesser quantity of magnetite. Gangue minerals are determined as calcite and quartz. REE data from the mineral samples demonstrate a range from 2.70 - 63.70 ppm and the average value is 28.00. These results permit a comparison to be made with mineralization in hydrothermal deposits. Moreover, mineral samples show a positive Eu anomaly 0.88-48.10 ppm (ave. 9.94 ppm). The Ce anomaly values vary between 0.02 and 0.88 ppm (ave. 0.58 ppm). It is possible that the mineralization may be affected by the mixing of seawater and hydrothermal fluids. The value of the positive Eu anomaly is evidence of modern oceanic hydrothermal manganese deposits. Insight of previous fluid inclusion, studies can be easily inferred that mineralization can occur at three different stages. The temperature of the first stage ranged from 338 oC to 428 oC and other stages vary from 269 oC - 317 oC and 143 oC - 236 oC, respectively. As a comparison, calculated salinity is higher in Type I fluid inclusions (1.9-14.7 wt.% NaCl equiv.) than Type II and III fluid inclusions (1.9-5.1 wt.%NaCl equiv.) It is possible that the mineralization was formed by the mixing of magmatic and meteoric waters.