Quote Originally Posted by Nekodar View Post
It was not. There was a chance of sand or oil in last chest at 2.3 release, but it was not 100% until later.
Sands were not added until 2.38 - and it was in the same patch that they changed the drops to guarantee two oils, sands, and unidentified tomestones total from the instance. (Sauce: patch notes)

And if you're having that much trouble getting a drop, you could always get a pre-formed party together for it...