Are the 'cave' minerals archerite (K,NH4)H2PO4 and biphosphammite (K,NH4)H2PO4 identical? A molecular structural study

► We have determined the molecular structure of archerite ((K,NH4)H2PO4) and biphosphammite ((NH4,K)H2PO4). ► These minerals are formed from the reaction of bat guano and calcite. ► The molecular structure of the two minerals appear to be very similar.