Here is a little one that I picked up on one of my trips to Lake Superior. I'm not positive what it is...maybe Thomsonite?
Thank you for visiting today. I hope you enjoyed my #fridaysrock post. The #fridaysrock tag was created as a place for those of us who enjoy rocks and minerals to share what we love. Please feel free to join in...on any day of the week.
If you enjoy rocks and minerals, you might enjoy the following:
#rockhound by 
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#fridaysrock by 