- (B) Phosphorus normally occurs in nature as part of a phosphate ion (i.e.,
orthophosphate), PO 4 3–. Most phosphates are found as salts (e.g., calcium,
phosphate, magnesium phosphate, etc.) in ocean sediments and sedimentary
rocks. Over time, geologic processes can bring ocean sediment to land, and
weathering will carry terrestrial phosphates back to the ocean.