Phosphorites

Phosphorite is a source of phosphate fertilizer. Submarine varieties occur principally in areas of oceanographic upwelling off western continental margins and off some eastern margins. They can contain up to about 25% P. Resource-motivated investigations on them have been carried out off Africa, the USA, South America and New Zealand, of which the most extensive were off New Zealand. These began in the 1970s but declined in the 1980s. To date, no submarine phosphorites have been mined.