Hg Hydrargynum in Greek which means liquid silver...being shiny is where the "silver" comes in
So where is it used? In pressure-measuring devices among other things. Of what particular value is it? It has a high density which requires less space
It is a good conductor of electricity. A useful component of electrical switches.
It is also used in dental filings (isn't it poisonous?), paints, soaps, batteries and fluorescent lights.
Mercury is the fastest planet in our solar system. The slowest? So if quicksilver were slow silver would it be of as much value? What does speed have to do with efficacy in this case?