hydrargyrum

Hydrargyrum is the traditional Latin name for the chemical element mercury, whose symbol is Hg. The name derives from Greek hydor, meaning water, and argyros, meaning silver. In modern usage hydrargyrum is rarely used outside historical or formal contexts, with the element commonly referred to simply as mercury.

Mercury is a dense, silvery liquid metal at room temperature. It has atomic number 80 and an atomic weight of about 200.59; its melting point is -38.83°C and its boiling point is 356.73°C. It is highly dense, with a density around 13.53 g/cm3 at room temperature, and it is a good conductor of electricity while being a relatively poor conductor of heat compared with many other metals. Mercury forms amalgams with many metals and occurs naturally mainly as the mineral cinnabar (mercuric sulfide, HgS).

Mercury is obtained commercially by roasting cinnabar to release mercury vapor, which is then condensed to liquid metal. It also occurs in the Earth's crust in trace amounts and in various mineral deposits.

Historically, mercury has been used in thermometers, barometers, and fluorescent lamps, as well as in electrical switches and dental amalgams. It remains in use in certain specialized applications, though many uses have declined due to toxicity and environmental concerns.

Safety and environmental considerations are central to mercury handling. Inorganic mercury and organic methylmercury are highly toxic, with exposure capable of causing neurological and renal damage. Methylmercury bioaccumulates in the food chain, particularly in aquatic ecosystems, leading to ongoing regulatory controls and remediation efforts worldwide.