RE:RE:POGIt depends on what yardstick you are using to determine the "top 10". If you use lowest AISC, then the #1 gold mine in the world (by a comfortable margin) is Fosterville, in Australia.
That is also the geologic model that Quentin Hennigh says NFG appears to closely approximate, so if the drilling proves up the concept, then NFG may indeed scale the ranks of the top mines. On top of that, the small amount of drilling they've conducted so far has encountered the high grade at much shallower depths than was the case at Fosterville.
Most of the major mines in South Africa are now very deep, even up to several thousand metres deep.