Tuesday, January 1, 2013

January 2013 Metal of the Month


        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.