The previous owners of this house left this bag ofblack sparkly powder in the shop. It is “slag” according to to the writing on the bag, which has now torn open forcing us to deal with this stuff. Can we use this in some way? We have a blacktop driveway; can we make it into a slurry or something to fill in cracks? Worth the bother, or just throw it away?
I had to see what that stuff is. It looks like coal slag
Ooh, thanks! That’s helpful. I just wish that website could tell me what the hell it’s used for. 
Well the website says it’s environmentally safe, and used in place of sand. So you could probably use it for anything you’d use sand for.
Try looking at the “products” link at the bottom of the page.
Here
It’s mainly an abrasive for sand blasting. It’s essentially just tiny little rocks or big grained sand. Mix it with soil if you have areas that need more drainage.
I use something similar for sand basting metal parts.
That website says a couple grades are good for sealcoating asphalt. I bet they planned to do that or possibly coat the garage floor and use it as a non skid additive.
it might be physically similar to sand, like same size particle. it is chemically different from sand, so it might be different if used as part of a soil mixture for plants.
Thanks, guys!
Measure it out into 50g bags and sell it to.model railway enthusiasts as ‘scale model coal’
You could mail it to some English person you don’t like.