Gold is called a “noble” metal

Gold is called a “noble” metal (an alchemistic term)
because it does not oxidize under ordinary conditions.
Its chemical symbol Au is derived from the Latin
word “aurum.” In pure form gold has a metallic luster
and is sun yellow, but mixtures of other metals, such
as silver, copper, nickel, platinum, palladium, tellurium,
and iron, with gold create various color hues
ranging from silver-white to green and orange-red.
Pure gold is relatively soft—it has about the hardness
of a penny. It is the most malleable and ductile of
metals. The specific gravity or density of pure gold is
19.3 compared to 14.0 for mercury and 11.4 for lead.