Cochise College Student Papers in Geology
Geology Home Page physical geology historical geology planetary gems
Roger Weller, geology instructor
wellerr@cochise.edu
Gold
Christina Lancaster
Physical Geology
Fall 2005
All About Gold
http://www.worldofrockhounds.com/huge-gold-nugget-sm.JPG
What is it?
Gold is derived from the Latin word aurum and is
known as the symbol Au on the periodic table of elements. Only the purest gold
is very soft and flexible, which easily can be hammered to a thickness of
0.000005 inches and be turned into wire that is 62 miles long. Most gold is a
bright yellow and is high in luster (very glossy). Other gold, which is finely
divided, is black and just small droplets of gold can range in color from ruby
red to purple.
Heat, air, moisture, and most solvents do not affect gold. However, mixtures that are extremely watery and containing several halogens, such as chlorides and iodides, will dissolve gold. The melting point for gold is at about 1947˚ F and boils at around 5173˚ F.
Ancient History
Fossil experts have observed that bits of natural gold had been discovered in Spanish Caves used by the Paleolithic Man about 40,000 BC. However, the first know use of gold dates back to 4000 BC in areas of central and eastern Europe. Archaeologists have discovered jewelry and art objects dating back to 3000 BC that were located in royal tombs in southern Iraq. Later the Egyptians used gold to please their kings in life and death and by 1500 BC, gold was introduced to the international trade business. Around 1200 BC in Peru goldsmiths made ornaments by stamping and hammering gold.
Credit photo to Latin American Studies: http://www.latinamericanstudies.org/moche/gold-artifacts.htm
Recent History – Value and
Production
With gold valued at $19.30 per troy ounce, the U.S.
congress, in 1792, adopted a bimetallic standard for the nation’s new currency.
In 1834, the price of gold rose to $20.67 and remained at that price for the
next 100 years. Franklin Delano Roosevelt, in 1934, devalued the dollar by
raising the price of gold to $35 per ounce. Over the next 46 years, the price
of gold per ounce rose dramatically, until about 1980 when it hit an all time
high of $850 per ounce. Since 1980, gold prices have been in a downtrend for
more than 13 years.
The production of gold dates back to the Etruscan,
Minoan, Assyrian, and Egyptian civilizations when placer gold was adopted from
alluvial sands and gravels by the process of washing or panning.
Around the time that the Americas were discovered, the
total gold stock value of Europe was probably less than $225 million. From the
end of the 15th century to about 1850, the world product of gold
totaled at 150 million troy ounces. During that time, South America and Mexico
became extremely large producers of gold. Because of Spain’s domination in
South America in the 16th century, the production of gold in the New
World increased by a large margin. This large increase is also due to the fact
of the simple seizure of gold from the Native Americans. In 1851, the discovery
of gold happened in Australia.
In the middle of the 19th century, the United States rose up in gold production. Gold of the United States only produced in two regions: the eastern region along the Appalachian Mountains, and the western region along the Rocky Mountains and Sierra Nevada, Coast, and Cascade Range. Gold first shipped to the U.S. Mint for the making of coins was from North Carolina in 1804. In 1848, American Pioneer, John Sutter, made the discovery of gold in California. It was not until long after that the Gold Rush hit, which caused many prospectors from all of over the world to travel to California. In 1911, gold was discovered in Alaska, from the boundary of the Canadian border to the Sixty Mile River. Today’s leading supplier of gold is Africa, which was producing 376 metric tons in 2003. About 70 countries, today, produce gold in wholesale quantities, but two thirds of the total worldwide production comes from South Africa, the United States, Australia, China, Canada, and Russia.
Where does gold occur?
Though scarce, gold is widely distributed through out
earth, being that it is 75th in order of abundance of the elements in
the crust of Earth. Gold occurs in seawater in weight 5 to 250 parts to 100
million parts of water. However, due to the 9 billion metric tons of gold
present in seawater, the cost of recovery would be greater than the value of the
gold that could be recovered. Gold occurs usually in association with silver or
other metals, in quartz veins or lodes, which are not visible because of being
so finely diffused.
Even though gold is rare, geologic processes concentrate the gold to form
profitable deposits of two principal types: lode and place deposits. Lode
(primary) deposits are the main points for the prospector seeking gold around
and/or in the site of deposition from mineralizing solutions. A concern for
prospectors or miners that are interested in a lode deposit of gold are that
they must determine the average gold content per ton of mineralized rock and the
size of the deposit. Placer deposits appear as concentrations of gold derived
from primary deposits by erosion, wearing down or decomposition of the
surrounding rock. These deposits formed in the same way throughout Earth’s
history. Surface placer deposits may be found under rock debris due to
weathering and erosion.
Credit Photos to the Mineral Gallery: http://www.themineralgallery.com/goldroom1.htm
What are the uses of gold?
Throughout history gold has been highly valued, not just because of its beauty,
but because it is easier to work with than other metals. A majority of the gold
is used in coinage, jewelry, and art. It has also been used in the world of
medicine, since 1927. In that time, it was discovered to be extremely useful in
the treatment of rheumatoid arthritis. Before that time it was used in
dentistry, in fillings and false teeth. Gold is used in lasers, which help
surgeons to seal wounds quickly or treat used-to-be inoperable heart conditions.
Below are several other major uses of gold.
· In 1908, the Olympic gold medal was first presented. The gold medal used today is actually made of silver and with at least six grams of pure gold.
· In the Galileo space probe, onboard computers are protected from short circuiting using Heavy Ion conductors made of not only silicon, but also gold.
· The robot, the Pathfinder, which took close-up pictures, used a high tech gold circuitry to transmit information back to Earth.
· Every telephone contains gold in the small transmitter in its mouthpiece.
· Airforce One, the airplane used by the U.S. president, uses gold-plated reflectors to protect it from heat-seeking missiles.
· The World Cup trophy is 32 cm high and is made of solid 18-carat gold.
http://images.google.com/images?svnum=10&hl=en&lr=&q=gold
Gold has been used in a variety of ways throughout history and in many cultures. Gold will continue to be valued by most cultures as a precious and valuable commodity.
Works Cited
http://en.wikipedia.org/wiki/Gold
http://encarta.msn.com/encyclopedia_761570498/Gold.html
http://pubs.usgs.gov/gip/prospect1/goldgip.html
http://www.answers.com/topic/gold
http://www.gold-eagle.com/gol_digest/history_gold.html
http://www.newmont.com/en/gold/goldfacts
