This is a sort of shale which contains minute grains of diaspore besides kaolinite.
There are nine layers of “aluminous shales” in permo-Carboniferous beds, which cover Ordovician limestone unconformably, and the layers are classified as A, B, C, D, E, F and G from upper to lower.
The shale is composed of kaolinite, diaspore, nontronite, rutile, sporogelite, halloysite, chlor-opal, and doelterite, and the granularities of crystals are as follows.
