I've been to the highest yielding part of one of the biggest gold mining operations in the world. I went 2.3km under ground, and down 6km of tunnels horizontall

I've been to the highest yielding part of one of the biggest gold mining operations in the world. I went 2.3km under ground, and down 6km of tunnels horizontally, to a part where they were getting 40 grams of gold per cubic ton of what is essentially hard rock.