MW (PO4) = 95 g/mol, MW (P) = 31 g/mol, MW (Mg2+) = 24 g/mol, MW (NH4+) = 18 g/mol, MW (H2O) = 18 g/mol. - - Struvite (magnesium ammonium phosphate) is a phosphate mineral with the formula: NH4MgPO4(H20)6. What is the molecular weight of struvite