Gold is a naturally occurring element (element symbol Au, atomic number
79), that is created in nature e.g. during supernovae explosions of type
II (see link "supernovae nucleosynthesis").
It also has been
created in amounts of a several atoms by nuclear transmutation (see
respective link), but it cannot be "created" or "destroyed" in the
classical sense of chemistry.
On earth, gold is found mostly in
solid form in veins in siliceous rocks. By alteration, it can be eroded
and placed in form of powder, granules or nuggets in the riverbeds. Low
concentrations of dissolved gold can also be found in the sea.Occurrence
in nature
Gold occurs in nature in both its native state and in
compounds. The native state of an element is its free state. It is not
combined with any other element. The most common compounds of gold are
the tellurides. A telluride is a compound of the element tellurium and
one or more other elements.
At one time, gold was found in chunks
or nuggets large enough to see. People mined gold by picking it out of
streams and rivers. In fact, gold was once very common in some parts of
the world. People valued it not because it was rare, but because it was
so beautiful.
The abundance of gold in the Earth's crust is
estimated to be about 0.005 parts per million. That makes it one of the
ten rarest elements in the Earth's crust. Gold is thought to be much
more common in the oceans. Some people believe as much as 70 million
tons of gold are dissolved in seawater. They also think there may be
another 10 billion tons on the bottom of the oceans. So far, however, no
one has found a way to mine this gold.
About a quarter of the
world's gold comes from South Africa. Other leading producers of the
metal are the United States, Australia, Canada, China, and Russia. In
the United States, about two-thirds of its gold is mined in Nevada.
California, Montana, Alaska, and South Dakota also produce gold.
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