The $300 million deal, which incorporates the Great Noligwa underground mine and related infrastructure, is expected to boost Harmony's operational cash flow by 60%.
The remote town of Nueva Fuerabamba was built to house around 1,600 people who gave up their village and farmland to make room for a massive, open-pit copper mine.
Democrats and environmentalists becoming increasingly concerned about why Interior Department remains silent about the National Academy of Sciences study.
The seeds of Tuesday's 4.6 percent copper slump -- the sharpest in almost three years -- were planted in a scarcely noted non-event earlier this month.