The chemical and physical properties of clay suspensions produced during oil production front oil sands are described. With a composition of approximately 70 wt% water (with some unrecovered bitumen) and 30 wt% solids (>90% less than 44 {mu}m in size), these clay suspensions consolidate very slowly. Clay aggregate or floc morphology has been shown to be a function of the water chemistry and can be manipulated to produce a tailings suspension that is easier to consolidate and dewater. Commercial oil sands processing has been going on in northeastern Alberta since 1967, and in that time approximately 250 million m of this difficult to dewater clay suspension has been produced. The reclamation options for this material (mature fine tailings) on a commercial scale are also outlined. 84 refs., 36 figs., 3 tabs.