Is it an ancient shaft straightener, either for arrows or for dart shafts--or possibly bone awls, those would require a hard, abrasive stone to turn a deer legbone into an awl--OR is it a pioneer knife sharpener--quite honestly I have asked myself the same questions over-and-over...still don't know. The stone is in the granite/ quartz family, pecked and polished to some degree, but still having a 'grainy' feel-likely the 'sandpaper feel' was what made it work. The piece was field-found, so there are a couple plow scratches--it's a southwest Indiana find, either Gibson or Warrick County, I never marked it when I acquired the piece twenty years back. Length is 3&9/16" by 2", 1&1/4" in height. The 'polishing groove' down the flat face is very symmetrical, but isn't use- polished. Both ends are deliberately made flat. The 'humped' face fits your hand, and the texture is coarse enough that it's easy to grip...guess it HAD to be. If you've seen something like it, Email me--I know it's real, but simply hard to classify. Shipping is $7.00, checks or M.O.s welcomed. Sorry, I do not use paypal--Roy A.