my son found these in a feild while hunting for arrowheads. Never seen anything like it and we have searched on google, but i just cant seem to find any matches.
These have all been scrubbed, and they all have a nearly waxy feel to them. A few are even a bit tacky to the touch. Does that sound right? (Off i go to do some research on shatter cones!!)
Test for hardness. Look up 'MOHS' Hardness scale...gather some things to make a test kit...that should help you zero in on what they are and what they aren't. They look fairly uniform in substance...you should easily be able to do a scratch/streak test, too.