crystal clathrate material clathrate compound material This class is not to be confused with CHEBI's "clathrate". The latter refers to the pure substance, while this class refers to clathrates found in nature. "Traditionally, clathrate compounds are polymeric and completely envelop the guest molecule, but in modern usage clathrates also include host-guest complexes and inclusion compounds." https://en.wikipedia.org/wiki/Clathrate_compound Not sure if this should be a subclass of crystal. If it is removed, remember to assert that it is a solid. A material which is primarily composed of a substance arranged as a lattice which can trap or contain other molecules. clathrate crystal material envoPolar