By: Kelly Snyder
Gold is a metal prized for its beauty, usefulness and scarcity. Gold is one of the most lustrous (shiny) metals. Its chemical symbol, Au, comes from aurum, the Latin word for shining dawn. Gold is a soft metal. It is the most malleable of all metals. Malleability is a metal's ability to be beaten or pressed into various shapes without breaking. Gold can be beaten into extremely thin transparent sheets. Gold is one of the densest metals. Gold weighs about 19 times as much as an equal volume of water at 20ºC (68ºF). One cubic foot (0.028 m3) of gold weighs over half a ton.
Gold does not rust like iron because it is unaffected by water or oxygen in air. Gold does not tarnish like silver because it is unaffected by sulfur compounds. However, gold dissolves in aqua regia, a mixture of hydrochloric acid and nitric acid. Gold is rarely used in pure form. It is usually combined with one or more other metals to form an alloy. Copper is the metal most commonly alloyed with gold.
Manufacturers express the proportions of gold in an alloy by:
- karats
- fineness
The karat system, which is usually used for jewelry and ornaments, divides the alloy into 24 parts. One karat (sometimes spelled carat) is equal to one 24th part. Therefore, 24-karat gold is pure gold. Jewelry made of 14-karat gold consists of 14 parts gold and 10 parts of some other metal or metals. The fineness scale, used mostly for industrial products, expresses the proportion of gold parts per thousand. Five hundred fine gold means the alloy consists of 500 parts gold and 500 parts other metal.
Since people have put such a high value on gold, its presence has attracted much attention throughout the ages. One of the main reasons for Spanish and Portuguese explorers taking an interest in South America was to plunder the region for gold.
The 19th century saw several gold rushes in the United States, Canada, Russia, South America and Australia. The 1848-49 gold rush in California produced more new gold than had been found in the previous three centuries and made the United States the largest gold producer in the world. But as these gold fields were worked out others took their place in Alaska, Australia and South Africa. Of the probable world gold reserves, about half are to be found in Witwatersrand area of South Africa.
Canada's history is closely tied to the discovery of gold within its borders. With the discovery of gold in California, every place west of the Rocky Mountains was considered a likely spot for another great strike. The first gold discovered in British Columbia was found on the Queen Charlotte Islands in 1850. By April 1858, the Fraser River Gold Rush was on in force. The Fraser River Gold Rush gave a tremendous boost to Vancouver, a sleepy hamlet of two to three hundred people. The gold rush precipitated development, changing the face of British Columbia and the Canadian West beyond recognition.
As early as 1873, men moved into the Klondlike, working creek beds of the mighty Yukon River and its numerous tributaries. In 1895, there were no people living where the Yukon and Klondike rivers flow together. By 1897, Dawson City was well established. It became the center of supplies for the gold field to which men were flocking in ever-increasing numbers, from all over the world. Dawson City in its heyday had grown almost overnight from a few log cabins to a bustling boisterous town filled with shops, restaurants, saloons, banks and, above all, people. It boasted sewers and sidewalks and plate-glass windows as well as its own telephone and electricity systems. The Yukon was a success for Canadian miners and mining. In the year 1900, about $22,000,000 worth of gold was produced in the Yukon; that was the peak year. Between 1885 and 1927, the total yield of the Yukon gold exceeded $175,000,000. Even today, the Yukon is still producing gold.
We may think that the discovery of gold in the Yukon is the most memorable event in the history of Canadian gold mining, but the discoveries at and near Kirkland Lake, Ontario, remain the most profitable. In July 1911, a solitary prospector by the name of William H. Wright discovered gold while prospecting in the Timiskaming District of northern Ontario. Six months later Harry Oakes was prospecting on the south-west of Wright's location and made a grub stake, that would later become the Lake Shore mine, which has the deepest mining shaft on the continent.
The finds of Wright and Oakes brought on a new burst of mining activity in the Canadian Shield. Gradually the communities of Kirkland Lake, Porcupine and Timmins grew in strength and size. Gold mining was not "a flash in the pan" here, but the area remained a gold-mining center into the 1950s, but by 1970, most of the mines in the area had closed and iron mining became the leading economic activity.
Throughout history, people have used gold mostly as money and for jewelry. Today, gold also has many other uses. All countries accept gold in payment for international debts, though such payments are not common. The world's governments hold about 42,000 short tons (38,000 metric tons or 38 million kilograms) of gold in their official stocks. Almost all of the gold is in brick-like bars, which are called ingots. The United States government stores its gold mainly in the Federal Reserve Bank in New York City and at a depository in Fort Knox, Kentucky. Gold bars are a form of bullion - that is metal held for its value as a metal rather than as money.
Gold is almost entirely non-reactive. Although this means the gold will not form compounds, it also means that, where non-reactive materials are needed, gold has an important part to play. Because it is rare, it is also expensive to use. This is why gold is used only where such materials are important.
Gold is a good conductor of electricity and does not oxidize, so it is important for use in electrical circuits, such as microelectronics, and for connectors and switches. Most of the gold used is electroplated on to some less expensive base material. Since it does not corrode, gold is used in places where there is a corrosive atmosphere such as certain chemical processes. For the same reason, gold can be used safely in amalgams to make dental fillings. Thin gold films on spacecraft reflect infrared rays from the sun, which can harm both people and equipment. A transparent gold film in windows of large office buildings also reflects infrared rays, helping to keep the buildings cool in summer. Artists used gold leaf, thin sheets of gold for decoration and lettering.
Uses for Gold:
- Aircraft - gold coated windows
- Artistic Work
- Automobile air bag deployment system, gold plated system sensors in the engine and exaust system
- Catalysts - used in chemical reactions for industrial applications
- Coins
- Computers
- Decorations
- Dentistry
- Electrical and Electronic Devices
- Eye surgery - eyelid load implants allow the eye to blink property.
- Fire Fighting - Firefighters wear gold coated protective shields to protect the eyes.
- Food freshness sensors - measure levels of carbon dioxide
- Jet Engines
- Jewelry
- Lasers for medical use, sealing wounds, rejuvinating skin tissue.
- Medical Field - Treatment of Arthritis
- Money - Gold Standard
- Photographic Films
- Radios
- Reflectors to confuse incoming heatseeking missiles
- Surgery - tools for clearing clogged coronary arteries, prostate cancer treatment.
- Space Industry - Heat Shields and Helmet Visors
- Telephones - in the diaphragm of the mouthpiece
- Televisions - T.V. Screens
- Thermometers - gold helps the thermometer to record the body's temperature in 2 seconds.
- Windows - coating to reflect infrared
Facts about Gold:
- A cubic room 18m per side could contain all the gold ever mined.
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The heaviest gold nugget - 90kg - was found in Australia.
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Depending on the ore, sometimes only 25 grams of gold is extracted from 13 metric tons of rock.
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South Africa is the largest producer of gold in the world.
School Activities
Science
- Make a list of the unique properties of gold and/or the various uses of gold.
- Write an essay on why alchemists failed to produce gold from another substance.
- Make a kit and conduct tests to compare different metals.
- Separate a mixture of sand and water using a coffee filter. Then, separate a mixture of sand and sugar by adding water to dissolve the sugar and pour the mixture through a filter to leave only the sand behind. Next, separate iron powder and sulphur using a magnet. Finally, separate salt from salt-water by allowing the water to evaporate.
- Metals may precipitate to form an ore. Inside the earth, metals seep into cracks forming veins of ore. To observe this phenomenon, place an iron nail in a bowl of water. Let the nail rust. Then, place a dry sponge in the bowl. A few days later the rust will be absorbed by the sponge "rock."
- Pan for gold in the classroom. Mix one quarter cup of "gold" - copper pellets or iron filings - with 10L of coarse sand and add water to make a slurry. Then, have students use shallow pans to swirl the slurry over another large pot. Continue to add water until only the pellets or filing are left.
- Build a small sluice box with wood, carpeting and chicken wire. Place the box at a 5-15 degree angle. Run a slow stream of water down the sluice and place some fine mixed materials on top of the sluice box. The heaviest material will be caught in the chicken-wire riffles.
- To demonstrate land reclaimation after mining, have students pour water - (demonstrating erosion) - over three mounds of soil, sand and gravel and then have students plant grass seeds on the three mounds. What happens? Try to explain the benefits of reclaiming old mine sites.
Social Studies
- Consider the possibilities for gold mining on the moon or profitably extracting gold from sea water.
- Read myths surrounding gold - Jason and the Argonauts, Tommy-knocker, King Solomon's mines, Blackbeard's treasure, Rumpelstiltskin, King Midas and the Lost Dutchman's mine.
- Check the newspaper for current gold prices and prepare graphs to illustrate how gold prices fluctuate.
- Write an essay on the use of gold as a monetary standard.
- Prepare and present a report on gold rushes throughout the world.
- Create a scrap book containing pictures of modern mining operations.
- Research mining superstitions.
- Research and prepare a report on the dangers involved in mining.
More Suggestions...
- Visit a mining operation in your community and discuss the mine's economic and environmental impact on your community.
- Contact a local geologist to identify nearby spots where students might pan for gold (or another "heavy" mineral).
- Investigate mining-related careers - metallurgist, geologist, mining engineer, chemical engineer, surveyor, driller, blaster, cartographer and environmental scientist.
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