Drops of mercury. Mercury or quicksilver is a dense, silvery metal which is liquid at room temperature. It is obtained from the mineral cinnabar (mercury suphide) and is used in electrical apparatus, thermometers & switches, industrial electrolysis, herbicides & pesticides and dental amalgams (alloys). Mercury, along with most of its compounds, is highly toxic to humans. It belongs to the zinc group of the periodic table and has the chemical symbol Hg.