The Cape Bentonite Mine deposits occur in the cretaceous beds in the Southern Cape, South of the Langeberge in the district of Heidelberg. Originally, it was formed by volcanic ash deposited during the formation of these mountains. The clay occurs in large beds dipping in a Northerly direction towards the mountains. All the beds are covered by a fairly soft siliceous sandstone layer, consisting mainly of Cristobalite and Quartz. The Cape Bentonite deposit is a Sodium-based Bentonite. Sodi...