Vendian-Cambrian Era of Phosphogenesis had taken place 650-530mys. with peaking in the Lower Cambrian (so-called "Pre-trilobite Cambrian"). That period of time was characterized by the broad development of firm skeleton be ings. The phosphate; bearing sediments are well known through all the continents (except the Antarctid) in the sequences of that age. The phosphate deposits are usually in association with the carbonaceous formations. The sedimentary lithological types of phosphorites are:

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... anic, microgranular, nodular, and organomorphic. The most typical are aphanic and microgranular. The aphanic and microgranular phosphorites are considered to be the products of chemical deposition. The phosphate-bearing mineral in phosphorites is mostly fluorine-carbonate-apatite.