Filo Mining has a huge copper-gold-silver deposit on the border of Argentina and Chile. And the company is getting deeper drill intercepts that suggest a much larger deposit underneath the open-pit resource they've defined. But it's low-grade, and that border is way up in the Andes where other companies have famously had problems before. Other big deposits in the region have been sold in recent years, mostly to the Chinese, and none have become mines yet. Is this really a good place to build a mine? And how do the economics work? That's what an independent speculator wants to know...Note that, as always, our interviews are neither endorsements nor recommendations of the companies covered.