I didn't do my "fact-checking" before I posted and had my Eagle "anatomy" wrong , so to speak. Not the throat after all.
At any rate, another possibility with the chromite being an EM insulator, does it "shield" impulses absolutely, regardless of thickness? Or every so often, where the chromite thins to mere centimeters, does it allow glimpses underneath?
The hit ratio for Ni-Cu sulphides is certainly explained by these revelations. At the very least, although the chromite seemed to stall the momentum of the RoF in recent months because of the infatuation with nickel, the chromite might well overtake the value of the nickel in the long run.
I ain't complainin' ! But you can see why this treasure at McFauld's lay hidden for so long...if it was easy, it would have been found before now.
GLTAL