January 2013 Metal of the Month
Gold
Gold is a dense, soft,
shiny, malleable and ductile metal. It is a chemical element with the symbol Au
and atomic number 79. Gold has a bright yellow color and luster traditionally
considered attractive, which it maintains without oxidizing in air or water. The metal therefore occurs often in free
elemental or native form, as nuggets or grains in rocks, in veins and in
alluvial deposits. Gold has been a
valuable and highly sought-after precious metal for coinage, jewelry, and other
arts since long before the beginning of recorded history. A total of 171,300 tons
of gold have been mined in human history, according to the GFMS as of 2011. This
is roughly equivalent to 5.5 billion troy ounces or, in terms of volume, a cube
measuring 20.7 meters on a side. Besides
its widespread monetary and symbolic functions, gold has many practical uses in
dentistry, electronics, and other fields. Its high malleability, ductility,
resistance to corrosion and most other chemical reactions plus conductivity of
electricity led to many uses of gold, including electric wiring, colored-glass
production and gold leafing. Most of the
Earth's gold lies at its core, the metal's high density having made it sink
there in the planet's youth. Virtually all of the gold that mankind has
discovered is considered to have been deposited later by meteorites which
contained the element. Native gold
occurs as very small to microscopic particles embedded in rock, often together
with quartz. These are called lode deposits. The metal in a native state is
also found in the form of free flakes, grains or larger nuggets that have been
eroded from rocks and end up in alluvial deposits called placer deposits. Such
free gold is always richer at the surface of gold-bearing veins owing to the
oxidation of accompanying minerals followed by weathering, and washing of the
dust into streams and rivers, where it collects and can be welded by water
action to form nuggets.
Gold is a dense, soft,
shiny, malleable and ductile metal. It is a chemical element with the symbol Au
and atomic number 79. Gold has a bright yellow color and luster traditionally
considered attractive, which it maintains without oxidizing in air or water. The metal therefore occurs often in free
elemental or native form, as nuggets or grains in rocks, in veins and in
alluvial deposits. Gold has been a
valuable and highly sought-after precious metal for coinage, jewelry, and other
arts since long before the beginning of recorded history. A total of 171,300 tons
of gold have been mined in human history, according to the GFMS as of 2011. This
is roughly equivalent to 5.5 billion troy ounces or, in terms of volume, a cube
measuring 20.7 meters on a side. Besides
its widespread monetary and symbolic functions, gold has many practical uses in
dentistry, electronics, and other fields. Its high malleability, ductility,
resistance to corrosion and most other chemical reactions plus conductivity of
electricity led to many uses of gold, including electric wiring, colored-glass
production and gold leafing. Most of the
Earth's gold lies at its core, the metal's high density having made it sink
there in the planet's youth. Virtually all of the gold that mankind has
discovered is considered to have been deposited later by meteorites which
contained the element. Native gold
occurs as very small to microscopic particles embedded in rock, often together
with quartz. These are called lode deposits. The metal in a native state is
also found in the form of free flakes, grains or larger nuggets that have been
eroded from rocks and end up in alluvial deposits called placer deposits. Such
free gold is always richer at the surface of gold-bearing veins owing to the
oxidation of accompanying minerals followed by weathering, and washing of the
dust into streams and rivers, where it collects and can be welded by water
action to form nuggets.
