Mercury

Mercury's symbol 'Hg' comes from 'hydrargyrum,' a Latin-Greek hybrid meaning 'water-silver' — and that name makes perfect sense when you see this silvery metal flowing like water at room temperature. Mercury is one of only two elements that are liquid at room temperature (bromine is the other). It has been known since ancient times — mercury was found in Egyptian tombs dating to 1500 BCE.

Old thermometers and barometers used mercury because it expands evenly with temperature. Mercury was also used in hats-making felt, causing neurological damage — this is the origin of the phrase 'mad as a hatter.' Today, mercury use is declining due to its toxicity, but it is still used in some fluorescent lights, dental amalgams, and scientific instruments. Mercury-containing batteries are being phased out worldwide.

Mercury's symbol 'Hg' is a unique two-letter element in Spellement. While 'hg' does not appear at the start of English words, partial emphasis lets spellers use 'h' or 'g' individually — both common consonants that provide useful flexibility for creative word building.