With an atomic number of 80, Mercury’s symbol comes from the Latin hydrargyrum, meaning "liquid silver”. The term “quicksilver” comes from Middle English and Old English (cwicseolfor), where cwic meant "alive" or "moving" and seolfor meant "silver."

Historically, quicksilver was used in alchemy, where it was believed to have mystical properties and was associated with transformation. Even today, the word "quicksilver" is sometimes used metaphorically to describe something elusive, fast-moving or unpredictable.

The modern English name mercury comes from the planet Mercury. In medieval alchemy, the seven known metals – quicksilver, gold, silver, copper, iron, lead and tin – were associated with planets. Quicksilver was associated with the fastest planet, which had been named after Mercury, the Roman god of speed and mobility. The astrological symbol for the planet became one of the alchemical symbols for the metal, and Mercury became an alternative name for the metal. Voilà.

Mercury is highly toxic, affecting the nervous system, kidneys and lungs, and is primarily found in cinnabar ore (HgS), which has been mined for centuries in regions like Spain, Italy and China. Despite its toxicity, mercury has been used in everything from thermometers to gold extraction, leaving an indelible mark on human history.

In the 18th and 19th centuries, hat makers commonly used mercury nitrate to treat felt, and prolonged exposure led to tremors, hallucinations, mood swings and dementia – giving rise to the phrase "mad as a hatter”. This is believed to have inspired the erratic behaviour of the Mad Hatter in Alice’s Adventures in Wonderland (1865).

The scientist Sir Isaac Newton also had a somewhat tragic connection to mercury. Later in life, Newton exhibited signs of paranoia, insomnia and irritability. Modern analysis of his hair found high mercury levels, likely due to his alchemical experiments, which involved handling mercury compounds.

The most devastating example of mercury poisoning occurred in the 20th century with the Minamata disaster in Japan. In the 1950s, a chemical factory dumped industrial waste containing methylmercury into Minamata Bay. The toxic substance accumulated in fish, which were consumed by locals, leading to severe neurological disorders, birth defects and death. Thousands of people were affected, and "Minamata disease" became a global symbol of environmental mercury poisoning. The scale of the tragedy led to increased awareness and regulations, culminating in the Minamata Convention on Mercury (2013), a global treaty aimed at reducing mercury emissions and exposure.

Today, mercury use is heavily restricted due to its toxicity, e.g. mercurochrome, a mercury-based antiseptic, was once widely used for wound care, but has largely been phased out due to those concerns. Having said this, mercury still has some specialised applications in electrical switches, scientific instruments and medicine.
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References

wikipedia.org/wiki/Mercury_(element)

Images

1. Mercury. Photo credit: adda247.com
2. The symbol for the planet Mercury (☿) has been used since ancient times to represent the element.
3. Periodic table element mercury
4. 1689 Sir Isaac Newton portrait young by Sir Godfrey Kneller
5. Mad Hatter, Walt Disney Animation Studios
6. Map of Minamata, illustrating the Chisso factory and its effluent routes
7. Mercurochrome [Ed: I remember]
8. Mercury thermometer