The present invention relates to crystals of (6a 9a) 5 6a 7 8 9 9a hexahydro 5 methyl 3 (phenylamino) 2 ((4 (6 fluoropyridin 2 yl)phenyl)methyl) cyclopent[4 5]imidazo[1 2 ]pyrazolo[4 3 ]pyrimidin 4(2) one and methods of making and using such crystals.