Metals of the Gold Rush

gold nugget

Native gold nugget

Gold

Symbol: Au

Atomic Number: 79
Melting Point 1064 °C
Boiling Point 2856 °C
 

Uses:

Gold is the most malleable and ductile of all metals. A single troy ounce of gold can be beaten into a flat sheet measuring roughly 5 meters on a side. Thin sheets of gold, known as gold leaf, can be as thin as 0.000127 millimeters, or about 400 times thinner than a human hair.

Pure gold is soft and is usually alloyed with other metals, such as silver, copper, platinum or palladium, to increase its strength. Gold alloys are used to make jewelry, decorative items, dental fillings and coins. Gold is a good conductor of heat and electricity and does not tarnish when it is exposed to the air, so it can be used to make electrical connectors and printed circuit boards. Gold is also a good reflector of infrared radiation and can be used to help shield spacecraft and skyscrapers from the sun's heat. Gold coated mirrors can be used to make telescopes that are sensitive to infrared light.

Measurements

Precious metals like gold are measured in troy ounces and troy pounds. The troy ounce is approximately 10% heavier than a typical grocery store (avoirdupois) ounce. A troy pound weighs approximately 17% less than a grocery store pound.

History:

An attractive and highly valued metal, gold has been known for at least 5500 years. Gold is sometimes found free in nature, but it is usually found in conjunction with silver, quartz, calcite, lead, tellurium, zinc or copper.
The gold deposits of the Klondike region were placer deposits. This meant the gold could easily be extracted by panning or sluicing and didn't require the need for heavy earth moving equipment or blasting.


 
silver nugget

Native silver nugget

Silver

Symbol: Ag

Atomic Number: 47
Melting Point: 961 °C
Boiling Point: 2162 °C

 

Uses:

Silver and silver compounds have many uses. Silver is very ductile and malleable, being just slightly harder than gold. It is the best known as the highest conductive metal of electricity at common temperatures and pressures. It is also the best reflector of visible light.

Silver has been used for coinage, used to make photographic films and papers and to make silverware, jewelry and other decorative items. Silver, like gold, can be shaped and transformed at room temperature by hammering.

History:

Silver has been known and used for at least as long as gold, nearly 5000 years. Silver is sometimes found free in nature but it is usually found in ores containing gold, lead, or copper. Early Greeks and Romans used silver to prevent infection. During the Middle Ages, it was used to disinfect water and food during storage. In the 1920s silver solutions were approved by the US Food and Drug Administration for use as antibacterial agents.


Silver occurs in either veins or alluvial deposits and is recovered by hard rock or placer mining. The silver deposits of the Klondike region were placer deposits. Although not as abundant as gold in the Klondike region silver was extracted by panning or sluicing and didn't require the need for heavy earth moving equipment or blasting.


 
mercury

Liquid mercury

Mercury

Symbol: Hg
Atomic Number: 80
Melting Point: -38 °C
Boiling Point: 356 °C

 

Uses:

Mercury is the only metal that is liquid at standard conditions for temperature and pressure. It has one of the broadest ranges of its liquid state of any metal.

Mercury was often used in thermometers, barometers, and some electrical switches, but concerns about the element's toxicity has led to many of these uses to end.

Mercury occurs in deposits throughout the world mostly as cinnabar. Cinnabar deposits were mined not far from the Klondike region allowing easy access to mercury which was used by the miners to extract fine gold. Thin mercury particles formed around fine gold. Using hydraulic type mining techniques, common during the Klondike Gold Rush, heavier gold particles would sink in the flowing water. Later the gold was recovered by burning off the mercury.

History:

Mercury has been found in both ancient Egyptian and Chinese cultures that date from 1500 BC. Its use was thought to prolong life, heal fractures, and maintain generally good health. The ancient Greeks, Romans and Egyptians were known to use mercury in cosmetics which sometimes led to disfigurement.

Many early alchemists viewed mercury as the First Matter from which all other metals were formed. They believed different metals, including gold, could be produced by varying the quantity and quality of sulfur and mercury.

From the mid-18th to the mid-19th centuries, a mercury compound, mercuric nitrate, was used in the making of felt hats. This process separated the fur from the pelt and matted it together. This solution and the vapors it produced were highly toxic. The psychological symptoms associated with mercury poisoning are said by some to have inspired the phrase "mad as a hatter."

 

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