The paper displays preliminary results of using the method of partitioning red-colored sediments on the base of spectrophotometric characteristics of their pigmenting fine-grained fraction. The rocks were differentiated by reflectance spectra of the surface of specimens prepared by precipitation of fine particles from water suspension on glass. The reflectance coefficients were measured with optical spectophotometer SPECORO 200 at various corners of the specimen inclination to a light ray. Tangents of the angle of slope of reflectance curve in different spectral regions and the color coordinates in the colorimetric system XYZ were used as numerical characteristics.