Hi, I recently purchased a stone that measures 1" x 2" x 8" and on the end of the stone it is stamped "made in USA". I cleaned it up and discovered it is a coticle. I have yellow coticule, so I put it next to the light grayish tan more grey than tan coticule. The edges have the same look of the sedimatary layers, at ten power the have the same apearence, except for the color . This stone is finer than yellow coticle, in fact it is finer finisher than my thurigan. It is the fastest finisher if ever had a hold of. It produces a grayish black slurry. holding to the light and sighting done the face it looks smoother than glass. I guess my question is, What is coticule doing with made in usa on the edge, where might this stone originated? The longer I collect stones the less I know about them.