Why does it "begger belief"? From a strategic operational perspective, I would not be surprised at all if they haven't sampled CZ31 at GR. In fact, I'd be surprised if they HAD. The Mississipian provided all they need from GR at present to progress the project. It makes no sense to take on more operational risk by plugging the Missi to move up and sample CZ31, to then plug CZ31 to move back down to Missi where they have been extracting from for the past couple of months. Remember the primary purpose of GR is to prove process in-field. That is exactly what they are doing.
What matters is that they prove infield process, then secure offtakes and finance. The pathway to achieving those goals is always fluid, changing in response to new info as it comes to light. Everything I see indicates to me that that is exactly what ASN have been doing.
