Sham, is that sedimentary layering on the side view of the stone or just dirt? There was a well known novaculite (Arkansas stones are novaculites) stone called the Hindostan stone which was found primarily or possibly even exclusively in the state of Indiana.
Hindostan was used often as a whetstone even for razors and was also used to make gravestones.
Here are some pictures that will probably not help all that much that I found on the net:
Thick/thin edge banding on the side of a Hindostan stone
Hindostan Gravestones
If you scroll down on that same site, there are some links to history papers about the whetstone industry in Indiana in the early 1800's.
I doubt yours is a Hindostan, but the color seemed similar. If yours isn't, then......SOMEONE go to Orange County, Indiana and get us some Hindostan whetstone!!
Chris L