Dark Green Glass type rock
Thank you for sending the pictures to us at eXtension. That is a fabulous find!
I personally have no skills in geology, nor can I find any geologist listed in eXtension. I would therefore suggest that you forward these pictures to some of the Purdue University geology staff, in hopes they can ID this for you. I would start with the following:
Darryl Granger: firstname.lastname@example.org
Nathaniel Lifton: email@example.com
Terry West: firstname.lastname@example.org
I truly don't know if any of these staff members can help you; however, please let them know, in your email, that I suggested you contact them. It may not help, but as my mother says, "It couldn't hurt!".