In article , Stormin Mormon wrote:

Does anyone wonder where mercury is, before it gets put in
the bulbs? Not like the make it out of nothing, you know.
Might be a chemically combined form that is less
troublesome.

Last time I checked, many years ago, the main source of mercury was its
sulfide ore, cinnabar. I imagine cinnabar and other mercury ores are safe
unless one eats them, or heats them to high temperatures that cause the
mercury compounds to break down and release mercury vapor.

- Don Klipstein )