Mercury

When gold was mined in Nova Scotia in the late 1800s and early 1900s, crushed rock was spread over liquid mercury. Gold particulates stick to the mercury, so the gold-bearing mercury could be easily separated from crushed rock. The mercury could then be evaporated, leaving the gold. Theremaining crushed rock as a sand-like substance known as tailings. It was typically dumped into low-lying areas of lakes and streams near the mine. The mercury was recovered for reuse, but some was lost through spills and has accumulated in the tailings. (Nova Scotia Environment)