Recently, we found a significant densification (with increased hardness) for BN and SiC when adopting a quartz-derived structure, i.e., qtz topology . The aim of the present work is to extend the model approach to equiatomic monophosphides of III A -group elements and to consider the possibility of their phase transitions at high pressure into superdense quartz-based hexagonal phases. Such high-pressure structures have been identified for zinc chalcogenides in addition to the cubic zinc-blende polymorphs adopted by the other II-VI compounds .