Phosphorus (P) is a nutrient necessary for all life. It enters the terrestrial food chain when it is absorbed by plants from soil. Soluble phosphorus is often a limiting nutrient in natural ecosystems. Large scale agriculture can rapidly deplete the soluble phosphorus in soil, leading to the need for topical phosphorus fertilizer. Phosphate rock is currently the only source of phosphorus for synthetic fertilizers and other industrial uses.
There are six phosphate rock deposit-types that are typically targeted for economic development: (1) marine phosphorites, (2) igneous apatite, (3) residual phosphorites, (4) river pebble phosphate deposits, (5) phosphatized rock, and (6) guano. Marine phosphorites are well documented within the Permian Phosphoria Formation of western to central Wyoming; these are the only phosphate rock occurrences in Wyoming likely to be of a grade and extent to attract economic interest. Geologic settings favorable to igneous apatite do occur within the central Laramie Mountains, and the Black Hills of Wyoming, but no extensive igneous phosphate rock deposits have been reported in Wyoming. The remaining four deposit types are not found in Wyoming.