rock that contains one or more phosphatic minerals of sufficient purity and quantity to permit its commercial use as a source of phosphatic compounds or elemental phosphorus, suure fosforisisaldusega (5-35% P?O?), enamasti merelise, harva mandrilise tekkega settekivim, mille fosfaatne aine koosneb peeneteralistest apatiidirühma mineraalidest (hrl. fluorkarbonaatapatiidist)