Homemade slate call?
 

Ok quite a while back someone gave me some home made slate call's I was wondering if anyone knows how to make one?He had some kind of wooden stick...I would like to know what kind...and some like black rock or something...anyone know what kind of rock to use for the slate and what kind of wood to use as the stick...also how would someone goes about getting the rock down to .25 inch thin


any responce and help is greatly appreciated