 Phosphorus comprises 0.1% by mass of the average rock (while, for perspective, its typical concentration in vegetation is 0.03% to 0.2%), and consequently there are quadrillions of tons of phosphorus in Earth's 3 * 1019 ton crust, albeit at predominantly lower concentration than the deposits counted as reserves from being inventoried and cheaper to extract; if it is assumed that the phosphate minerals in phosphate rock are hydroxyapatite and fluoroapatite, phosphate minerals contain roughly 18.5% phosphorus by weight and if phosphate rock contains around 20% of these minerals, the average phosphate rock has roughly 3.7% phosphorus by weight.Some phosphate rock deposits, such as Mulberry in Florida, are notable for their inclusion of significant quantities of radioactive uranium isotopes.This syndrome is noteworthy because radioactivity can be released into surface waters in the process of application of the resultant phosphate fertilizer (e.g.