The disclosure relates to a composition comprising an acid addition salt of (+)-I-(3,4-dichlorophenyl)-3-azabicyclo[3.1.0]hexane enriched for a selected polymorphic form of said acid addition salt of (+)-1-(3 ,4-dichlorophenyl)-3-azabicyclo[3.1.0]hexane selected from: Polymorph A, Polymorph B and Polymorph C, each exhibiting an X-ray powder diffraction pattern as measured at crystal sizes of from about 10 to 40 microns characterized by distinguishing peaks at one or more of and at about the 2-theta (degree) values defined in the specification. Also disclosed is a process for producing said Polymorph A, Polymorph B and Polymorph C.
