Although it is a metal, it is soft enough to be cut with a knife. It is so light that it can float on water. Fires caused by lithium are difficult to put out. You can't use water because it reacts with the lithium and could make the fire worse. A powder extinguisher is required. Along with hydrogen and helium, lithium was one of three elements produced in large quantities by the Big Bang. When burning, lithium emits a bright red flame. Because it is the lightest metal, it can be alloyed with other metals such as aluminum and copper to create strong, lightweight metals. Lithium hydroxide can be used to purify air and remove carbon dioxide in spacecraft and submarines. Say no to plagiarism. Get a tailor-made essay on "Why Violent Video Games Shouldn't Be Banned"? Get an original essay Lithium makes up just 0.0007 percent of the Earth's crust, according to Jefferson Lab, and is found locked up only in minerals and salts. Those salts have the power to change the brain: According to the National Institute of Mental Health, lithium salts were the first drugs approved by the Food and Drug Administration to treat mania and depression. Today, lithium carbonate is the compound most often sold as a pharmaceutical substance. Oddly enough, no one knows exactly how lithium works to stabilize mood. Studies show multiple effects on the nervous system. In 2008, for example, researchers reported in the journal Cell that lithium disrupts the activity of a receptor for the neurotransmitter dopamine. It also appears to increase brain volume, according to a 2011 study in the journal Biological Psychiatry (though this research is hotly contested). Lithium-ion batteries are the key to lightweight, rechargeable power for laptops, phones and other digital devices. According to the US Geological Survey, in 2014 alone Argentina and Chile increased their lithium production by 15% each to meet growing demand. Globally, production increased 6% that year. The United States has one lithium mine, in Nevada, according to the USGS. Chile and Australia produce the most lithium in the world. According to a 2009 study highlighting lithium's role in the brain, naturally occurring lithium in drinking water is linked to lower levels of suicide. But psychiatrists are cautious about prescribing lithium in high doses, especially because it can pass through the placenta and have unknown effects on the developing fetus. According to physicists, lithium was one of three elements produced in large quantities during the Big Bang. The others were hydrogen and helium.