Mercury, which usually appears as a thick silvery fluid, is the only metal that’s liquid at room temperature. Its elemental symbol is Hg, which comes from the Greek word “hydrargyrum,” meaning “liquid silver.” In fact, it’s also called quicksilver.
We use mercury in a wide range of products, from thermometers and barometers to batteries and pesticides. But mercury is extremely poisonous, and we can absorb it by touch, inhalation, or consumption. It builds up in the body with each exposure and is very difficult to remove. If you get too much in you, you can suffer from mercury poisoning, which is both unpleasant and potentially fatal.
That’s why you have to be careful not to break a mercury thermometer or a compact fluorescent lightbulb. It’s also why people are concerned about mercury in industrial waste and pesticides flowing into rivers and oceans and being absorbed by fish … which are then eaten by people.
But where does mercury come from, and how do we get it?
Most mercury is mined from a mineral called cinnabar, which can contain up to 86 percent mercury. People have been extracting mercury from cinnabar since at least Roman times. Veins of the red-to-brownish mineral are usually found in rocks such as slate, limestone, shale, and sandstone. A rarer form of cinnabar appears as striking deep red crystals embedded in other rocks.
How do we get the mercury out? Cinnabar is crushed into small pieces and heated in a kiln. When the temperature hits 675 degrees Fahrenheit, the liquid mercury becomes a vapor. As that vapor cools, the mercury condenses into a pure liquid that can be collected.
Cinnabar is mined all around the world, including Spain, Austria, Hungary, and Serbia. The United States has a number of cinnabar mines, including several in California, Texas, and Nevada.