Crack in black tank? Is it ABS or Polyethylene?

It turns out there is/was a yellow ABS cement. I found it listed on random small store websites, but not on Amazon. It's the same as the black, but yellow so you can better see the weld. It only works on ABS. I can't find anything yellow that binds polyethylene to ABS. So I'm thinking the tank is most likely ABS. When I drill the holes at the ends of the crack, I'll collect some shavings and see if they desolve in ABS cement. If they do, the tank is ABS for sure.