The dielectric relaxation model that takes into account the contribution of three relaxation processes into dielectric constant is used. The first relaxation process is caused by orientation polarization of the water molecules. The second and third processes are caused by polarization of water-air and water-mineral interfaces. Relaxation processes are described by Debye and Cole-Cole's formulas. To determine the model parameters the measurement of the complex relative permittivity (CRP) of the quartz globule powders moistened with distilled water and salt solution are made. The effect of particle size and concentration of the saturating solution on the model parameters has been established. The strength of the relaxation process caused by polarization the water-air interface reaches the maximum at an average saturation level, when the specific area of this interface is close to maximum. At that, the real part of CRP at a frequency of about 1 MHz may be greater than at full saturation.