The phosphate ion is almost insoluble and is one of the most inactive of soil's most abundant phosphate minerals. So how could phosphate have originally been incorporated into ribonucleotides,the building blocks of RNA, which are considered to be among the earliest constituents of life? American and Spanish scientists have now identified fair conditions to mobilize phosphate from insoluble apatite minerals for prebiotic organophosphate synthesis, or including ribonucleotides. The pivotal role of urea in this process is also described in their article in the journal Angewandte Chemie.
Source: phys.org