While the exact date and person who first discovered mercury is unknown, it's likely that ancient civilizations were aware of its existence.

Here's why:

* Ancient Egyptians: Used mercury in the 16th century BC for medicinal purposes and in the process of mummification.

* Ancient Greeks: The Greek philosopher Theophrastus (around 300 BC) described mercury as "liquid silver."

* Ancient Chinese: Used mercury in alchemy and medicine, dating back to the 7th century BC.

So, it's more accurate to say that mercury was known to ancient civilizations rather than a single person discovering it.