Yes, it’s simply a way to maximize the benefit of cooperation for an agent. Cooperate until the other agent steals then punish immediately but don’t hold a grudge about it and go back to cooperation. It’s relatively simple to simulate and it’s the most fruitful strategy.
Mercury alone is safe enough to handle a bit where you would be mostly worried about breathing too much of its vapor. Organic compounds of mercury on the other hand can kill you within days of a drop touching your skin.