Carbonates and phosphates are highly important in biomineralization. They are found as hydroxyapatite (Ca5(PO4)3OH) in bone or calcite/aragonite(CaCO3) in seashells and corals.These biogenic minerals are commonly formed from amorphous precursors (APs). To control the properties of the AP, foreign ions are incorporated to increase stability and direct polymorph selection. In a previous experiment we have studied amorphous calcium carbonate (ACC) with Neutron/x-ray pdf and EPSR and found structural similarities between water molecules and calcium ions in ACC and that of a Ca ion in solution. We now would like to extend this study to a mixed phase calcium carbonate/phosphate (ACCP) of defined composition to understand how the structural relation between the ions is affected by the presence of a foreign anion.