Figure 1: Chemical structure of the seven isomers of HCH. The isomers of HCH differ in the spatial orientation of the chlorine atoms around a central cyclohexane ring. Equatorial positions are shown in blue color while axial positions are shown in red. The alpha isomer has three axial and three equatorial chlorine atoms, and it also exists in two enantiomeric forms. The isomers η-HCH and θ-HCH are produced in minute quantities.