>How about mercury?  It was used for gilding - when was it "discovered"?
Does mercury occur in its usual shiny liquid state naturally?  How does one
"mine" mercury?  (especially if it's oozing away from you as you dig a hole
in the ground or whatever)<

In response to Steve's question about mercury I can do no better than
Hoover's translation of Agricola.

>The ores of the other metals are not smelted in furnaces. Quicksilver ores
and also antimony are melted in pots, and bismuth in troughs.

I will first speak of quicksilver. This is collected when found in pools
formed from the outpourings of the veins and stringers; it is cleansed with
vinegar and salt, and then it is poured into canvas or soft leather, through
which, when squeezed and compressed, the quicksilver runs out into a pot or
pan. The ore of quicksilver is reduced in double or single pots. If in
double pots, then the upper one is of a shape not very dissimilar to the
glass ampullas used by doctors, but they taper downward toward the bottom,
and the lower ones are little pots similar to those in which men and women
make cheese, but both are larger than these; it is necessary to sink the
lower pots up to the rims in earth, sand, or ashes. The ore, broken up into
small pieces is put into the upper pots; these having been entirely closed
up with moss, are placed upside down in the openings of the lower pots,
where they are joined with lute, lest the quicksilver which takes refuge in
them should be exhaled. There are some who, after the pots have been buried,
do not fear to leave them uncemented, and who boast that they are able to
produce no less weight of quicksilver than those who do cement them, but
nevertheless cementing with lute is the greatest protection against
exhalation. In this manner seven hundred pairs of pots are set together in
the ground or on a hearth. They must be surrounded on all sides with a
mixture consisting of crushed earth and charcoal, in such a way that the
upper pots protrude to a height of a palm above it. On both sides of the
hearth rocks are first laid, and upon them poles, across which the workmen
place other poles transversely; these poles do not touch the pots,
nevertheless the fire heats the quicksilver, which fleeing from the heat is
forced to run down through the moss into the lower pots. If the ore is being
reduced in the upper pots, it flees from them, wherever there is an exit,
into the lower pots, but if the ore on the contrary is put in the lower pots
the quicksilver rises into the upper pot or into the operculum, which,
together with the gourd-shaped vessels, are cemented to the upper pots.

The pots. lest they should become defective, are moulded from the best
potters' clay, for if there are defects the quicksilver flies out in the
fumes. If the fumes give out a very sweet odour it indicates that the
quicksilver is being lost, and since this loosens the teeth, the smelters
and others standing by, warned of the evil, turn their backs to the wind,
which drives the fumes in the opposite direction; for this reason, the
building should be open around the front and the sides, and exposed to the
wind. If these pots are made of cast copper they last a long time in the
fire. This process for reducing the ores of quicksilver is used by most
people.<

Discovered before records began as it occurs native. Mentioned by Aristotle
350 BC.

The usual ore, cinnabar/vermillion/mercuric sulphide, can be oxidised to
mercury and sulphur dioxide at fairly low temperatures (it burns in air). We
used to do this in school but we did it in a fume cupboard!

Apologies for any OCR errors I have missed.

Peter Hutchison