[meteorite-list] Meteorwrong; What Is It?

[JoshuaTreeMuseum]

Of all the Meteorite Men engendered meteorwrongs and leaverite that's been 
brought to the museum lately, this one was the most interesting.  It was 
found in southern Michigan by the area's largest rock dealer, (for 
landscaping and decorative use).  I know it's not a meteorite, but I'm not a 
geologist and can't identify it.  I thought it was some kind of rock slag, 
possibly volcanic in origin.  (Yes, I know there are no volcanoes in 
Michigan.)  People always want to know what it is if it's not a meteorite. 
Any ideas?

http://i190.photobucket.com/albums/z126/tboswell/April2010/001.jpg

http://i190.photobucket.com/albums/z126/tboswell/April2010/002.jpg


http://i190.photobucket.com/albums/z126/tboswell/April2010/005.jpg

Thanks in advance,

Phil Whitmer