You nailed it ! I find this quote funny: "Silver metal was added...

You nailed it !

I find this quote funny:
"Silver metal was added to the smelt for both flux A and flux B to test whether the addition of silver would aid the extraction of gold into the copper bar. In all cases where silver was added the levels of silver recovered were below the quantity of silver added."

As seem, the deeper they go, the less gold they found, and it shows less than ordinary grade. A big disappointment to many wishes of 10oz per ton gold mine !

Not to surprise to see the final uneconomical out come for this gold mining operation in the Amazon jungle !