Really nice looking coyotes you have there. If there is such a thing......jk

So I have some questions about this “coal shale”. Not as it relates to trapping. I am involved with making pottery and teaching about my specific niche in the ceramic field (I replicate native American artifact pottery). Through this I have learned a lot about clay science and geology and such stuff as that.
Coal often has both an “underclay” and an “overclay” layer. Now shale IS clay. Slate is metamorphosed shale. Shale can often be ground up or weathered into clay suitable for various ceramics.
I don't want to offend Vinke and write a dissertation here, but does anyone know the geology/classification of “coal shale”? Is it a true shale? Is it coal that looks like shale? Something else?

Coal shale is actually coal, just a broke down form of it. Sometimes when you start digging into a seam you will run into big chunks.

Thanks Tray!