I hope he's kidding, but if it's the appearance of crystals they're going for (mmmm, sugar coating!) the pieces of glass would be flipping tiny, too small to give you any lacerations, though getting that shit in your lungs is far from good (I'm thinking along the lines of people who sprayed insolation back in the day, well, at least in the states)

I've heard of people in the US doing crap like that (in the 80s or early 90s there were a rash of buds that were dusted with something along the lines of PCP). Unfortunately it's a case of you've got to know your supplier.

Does the UK still mostly have "soap" hash? That's the same sort of thing (though I suppose the soap mixture nearly as bad/evil/whatever as ground glass.)

Spirit: what part of England are you in?