Prospective reserves of coquina phosphorite deposits in Estonia and the Leningrad Region are estimated at 2–3 billion tons. Genetically, they are associated with a thickness of quartz–obolus sandy sediments of the Pakerort horizon of the Early Ordovician, distributed over almost the entire territory of Estonia and stretching 320 km to the east into the Leningrad Region. The thickness of the productive strata varies from 1 to 6 m, with an average thickness of 4 m. Phosphorite-bearing sandy sediments with erosion lie on sandstones, siltstones or clays of the Cambrian.