The last word, from the eminent Prof. D. Mattey? 09:03 Jan 26
As the name suggests a paper shale is one that splits into paper-thin layers. Normal shale splits easily but into thicker layers, typically > 1-2mm. Shale is clay that has been compressed by burial such that the tabular 'clay minerals' (a bona fide name given to a large family of silicates with sheet structures like mica) become aligned normal to the axis of compression, causing planes of weakness. Paper shale presumably has a higher content of clay minerals, or larger flakes. Schist is shale compressed and heated so new minerals form such as mica, giving the rock a silvery appearance, the layers become distorted and folded as well, not planar. Paper schist is the same as above, but quite rare (to me). Paper shales are fairly common.
Foliation means planar layers formed by growth of new minerals created by heat/pressure and is the defining feature of a schist but not normally applied to shale. Paper means thin layers and is not normally a term associated with schist. If it were a thinly foliated schist it should properly be called paper foliation. Structural geologists bandy foliation around and apply it to any rock that splits into layers, but this is incorrect | 
The translation workplace 
peer agreement (net): +3
