The oldest known mine in America was, it seems, a iron oxide mine from Chile, dated to as early as 12,000 years ago.
The mine in Taltal
, in today’s Northern Chile, was used first between 12,000 and 10,500 years ago and then again since 4300 years ago. More than 500 hammerstones dating to the first use of the mine reveal an unusual interest for such an early exploitation.
Source: Science Daily
. (Paper to be published in Current Anthropology next month).
The mine was previously mentioned, in greater extent, here.
Update (May 26): in the comments’ section it was mentioned that another, no so old, quarry is known to have existed in Virginia, where the first inhabitants extracted red jasper. The site is dated to c. 10 Ka BP and you can read about it here and (if you have a Science subscription) also here.