It's a paper on the epithermal deposit of Cinco Minas. Here's an interesting link on what an epithermal deposit really is and forms. https://www.911metallurgist.com/blog/epitherm...cteristics . Interesting are these lines in the link:

"Why are epithermal deposits important?
Well they are a major source of gold, providing about 12% of the world’s annual gold production, in fact they are the second largest producers of gold globally after the Witwatersrand deposits."

Witwatersrand deposit from Wikipedia: The Witwatersrand Basin is a largely underground geological formation which surfaces in the Witwatersrand, South Africa. It holds the world's largest known gold reserves and has produced over 1.5 billion ounces (over 40,000 metric tons), which represents about 50% of all the gold ever mined on earth.