Diatomite is fine-grained fossil siliceous sedimentary rock. It consists of micronized amorphous silica with a special porous structure. In this study, a technological diatomite sample was subjected to characterization by XRD, XRF, SEM and TEM techniques. Results showed the high grade of the sample with silica content exceeding 90% SiO2. The main accompanying minerals were fine sands, calcite, and kaolinite. The sample was subjected to gentle size reduction to avoid ore cell destruction. The attrition +74μm fraction was rejected, where the -74μm slurry continued refining via the 7.62cm Sprout Bauer and the 5.08cm Mosley hydrocyclones. The -25μm fraction was investigated as the final refined diatomite product.