Mercury (Hg), atomic number 80, is a silvery liquid used in thermometers and barometers. It is most commonly obtained by the reduction of the mineral cinnabar. Mercury is used in electrical apparatus, catalysis, poisons and dental amalgams. This image also shows its incredible reflective properties. Mercury, or quicksilver, is a dense, silvery metal which is liquid at room temperature. It freezes at -38.9 degrees Celsius.