KEYSTONE, S.D. (AP) - Work has resumed at a gold exploration drilling site in western South Dakota where a leak occurred last week.

The site was shut down when bentonite leaked into Battle Creek near Keystone. Bentonite is a claylike material used as a drilling lubricant. The Rapid City Journal reports that state officials do not expect any environmental damage.

Mineral Mountain Resources Ltd. of Vancouver, British Columbia, is exploring for gold in the area.

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