The paper includes data of the enclosing sediment, iron ore and groundwater composition within Bakchar iron ore cluster. Based on the water chemical composition analysis the thermodynamic equilibrium was calculated for enclosing sediment-groundwater-secondary sediments system, and being correlated to existing geological data. According to thermodynamic calculations, water is non-equilibrium to primary enclosing rock aluminosilicate minerals in which they dissolve and, consequently, are enriched by these chemical elements: Fe, Ca, Mg, K, Na, Si, Al, Mn and others. These accumulated elements in the solution provide clay-water equilibrium, carbonate-water equilibrium, Fe oxides and hydrooxides-water equilibrium.