I found a few of these beneath a train trestle outside of Nashville TN. We are currently arguing over what we think it is. It’s not magnetic. Any ideas? Thanks!
Pretty much impossible to tell what it is from the pic. Try the usual tests, hardness, streak, etc. To my eye it looks like it has an iridescent look very much like what I find on slag from the mines here in Butte. It looks very much like slag. JMO.