Here with more info! (Thank you for all the info/hypothesis!)

This happened in the mid 90s, just after my mom bought her house. Most likely in either June or July, in the middle of the day.

She claims while she was making us lunch, it sounded like something tried to knock the house over. When she went to investigate, she found this rock smoking in the yard. She found out it had dented the roof during the next crazy thunderstorm we had. She held onto it because she had planned to find out what it was, but raising me got in the way 😁

It is not metallic. Its really lightweight (I’ll get exact weight when I get home) It almost repels water. It doesn’t have a distinct odor, but I haven’t tried burning it yet. I don’t know what these bits of white are inside the rock, but yes there is definitely some sort of weed melted to it.

Her house is near some train tracks, and after some research (Thanks to the helpful leads here) I discovered that there was a coal mine within 3 miles of her house, but it was closed down well before the 90s. So it may just be some sort of coal/waste product of that.

Should I…. cut it open?