What type of things should we know when determining grinding stones vs river rocks

[sweetmimzim3]

What are some indications that a rock is a grinding stone vs a river rock. I guess as a non expert it is hard for me to determine whether a rock in hand created something or a rock rolling in the river. Here is a picture example of a rock I found that Im sure is just a river rock, but intrigued me by its shape.

 

[Tnmountains]

It really depends upon where you are and the type of rock and the culture it was associated with and what is was used for. I know that sounds confusing. But western verses eastern is different due to material and food source.
Later cultures had more time to create to elaborate items for the kitchen. Early cultures spent their skills on the flint.
Remember that the mortar and pestle had to be able to with stand working with each other for the task. When looking at a cupulet see if it would with stand use wear. Hope some of this makes sense.

 

[sweetmimzim3]

Makes all the sense in the world to me, thanks. I determined this not to be an artifact because of the material. Still a cool rock though.

 

[monsterrack]

Grinding stone will have the shape of a bowl like the ones in your kitchen and will show wear on the bottom and the sides. I would have pick up that rock myself and brought it home