Where I'm from we have had mass's of 'grit weed' over the last year, but not as of recent.
It's unfortunate that you purchased grit weed, but its only an 8th you have, so learn from it. Ask to see the weed if its possible with the person you are dealing with, and ASK if it contains grit. Sounds simple, but it will get you the information you want before parting with your money.