Hey, at least it burns!
" /> One antique machinery club we took my traction engine to had a large quantity of old "coal" donated to them by a local company that had been changed over to electric many years before. Boy, what a bargain!
After you removed the dirt, shale, rocks, pop cans, trash (well, okay, the old rags would burn), you still had something (much like your "bug dust", except it was pretty wet) that tended to give off a nasty oily smoke and bake into a large lump of crap that almost defied breaking up with a slice bar (even mixed with wood, it was a pain to keep lit).
I think they ended up using most of it for fill when they built the foundation for their sawmill.