This study investigates the major and trace element geochemistry of Bigadi borate deposits, the largest colemanite and ulexite deposits in the world. The known borate deposits of Turkiye were deposited in the lacustrine environment during Miocene when the volcanic activity occurred from Tertiary to Quaternary. All of the Turkish borate deposits are classified as volcanic related deposits. Boron ore deposits intercalated with claystone, mudstone, tufa and fine layered limestone show lens shape. Borate minerals formed in two zones. Tiilu and Acep-Simav open mines represented the lower and upper borate zones, respectively. Colemanite and ulexite are dominant minerals at all ore zones. The major elements of Bigadi borates contain Ca, Si, Mg, Al, Fe, S, Na, P and Mn at Tiilu, Ca, Na, Si, Mg, S, Al, P and Mn at Simav, and Ca, Na, Si, Mg, S, AI and Mn at Acep samples respectively. Except for Li, Mo, Sb, As, Sr and Se, concentrations of other trace elements are significantly lower than averages of earth crust and andesite at the three mines. With respect to averages of earth crust and andesite, Mo, Sr, As, Li and particularly Se are enriched significantly in the Bigadi. In examining depth-dependent variations of major and trace elements, four element groups at the Tiilu site and six element groups at the Simav and Acep sites were determined. Element abudances or element geochemical trends show differences at the Tulu, Simav and Acep mines. These differences can be explained by the diversity of physicochemical conditions in the deposition environment by the effect of differences at the recharge regime and source.