I live pretty close to the Arkansas River and it is a mile wide and full of fine sand and sand polished rocks of all descriptions. There are many colors of polished rocks that are just as finely polished as a tumbler on the sandbars. I use to go and collect them when I was a kid. But don't tell my Mom, lots of kids drowned in that old River and she would throw a fit if she knew I had been down there alone! Monty