khareema's comment:
"From what I have been told, the problem is part drilling and part lab. The situation is that the deep drills were designed and built specifically for the ROF. Once in service they realized that since the material being drilled is so much denser ( and heavier) at these greater depths, the drills do not have the capacity to lift it out of the hole. This then creates a second problem as the lab they are using has everything calibrated to process material of much less density ( weight), and none of their assay results can be relied on."
This brought to mind page 111 The Big Score, Amazing grade.
"What Sparkes and Verbiski had just seen was 104.3 meters of gleaming brassy core, all of it massive sulphides, twice the depth of massive drilled at No.2 in October. In a few weeks they would learn that core from No.7 averaged 2.96 percent at No.2. No wonder the Okuatsiaks had struggled with the boxes. Sulphide minerals are extremely heavy and the rich ore from No. 7 probably added 20 kilograms to each box. Sparkes had never heard about such massive sulphide in his life. But it wasn't the quantity that overwhelmed him; it was the size of the pentlandite crystals that held the nickel. Geologists has marvelled at the fingernail sized crystals of pentlandite from hole#2. But these crystals were something different. They were as big a Ping Pong balls."
I would prefer basketballs but would still be pleased with those ping pong balls.