This protocol describes a discontinuous gradient, which resolves the mitochondria from both lighter and denser organelles. Because the centrifugation is carried out for 4 h, diffusion will create a partially continuous gradient and this probably contributes to the resolution of the mitochondria from the lighter lysosomes. - [Read Purification of Mammalian Liver Mitochondria by Flotation Through a Pre-formed Discontinuous Iodixan]