Don't know if Panda Hill is so much better than Mt Weld, but I noticed the 20.6Mt you're quoting for PH is the ore reserve, not the resource, which stands at 178Mt @0.5% Nb2O5.
I also noticed that the niobium at Md Weld is included in the resource, but not in the ore reserve, so perhaps it's just a question of insufficient work having been done at this point to demonstrate viability.
Other thoughts anyone?
CXX Price at posting:
25.0¢ Sentiment: Hold Disclosure: Held