native material tests ready For bisque firing

I'm interested in learning what is the outcome as I'm living in an area (Andenne in Belgium) 8where there was clay digging industry from the 16th up to the 19th century and you can still collect some quantities of very nice white plastic clay called "derle".

I would say go out and grab some, doesn't have to be much.  Clean any large chunks and debris out if it fires up strong and non-porous you have (probably) hit paydirt.  If not it can have a few possible alternate lives....