Gold is one of the most precious metals in the world. It may have been the first metal used by humans and was valued for ornamentation and rituals. Nearly two thirds of the world's output of Gold comes from Africa, and about two thirds of the U.S. output of Gold comes from South Dakota. Gold has long been considered one of the most precious metals, and its value has been used as the standard for many currencies in history. Gold is dense, soft, shiny and the most malleable and ductile substance known. Pure gold has a bright yellow color traditionally considered attractive. Pure gold is too soft, and is usually mixed with other metal alloys (silver, copper, nickel and zinc) to make it stronger and more durable for jewelry. Gold has been called the most beautiful of all chemical elements. Its beauty has made it desirable for use in jewelry, coins, and artwork for thousands of years. Large amounts of gold are still used in the manufacture of coins, medals, jewelry, and art. Gold also has a number of uses in industry, medicine, and other applications.
Element gold
Symbol : Au
Name : Gold
Atomic Number: 79
Atomic Weight: 196.966569
Physical properties
Gold is quite soft. It can usually be scratched by a penny. Its melting point is 1,064.76°C (1,948.57°F) and its boiling point is about 2,700°C (4,900°F). Its density is 19.3 grams per cubic centimeter.
Two other important properties are its reflectivity and lack of electrical resistance. Both heat and light reflect off gold very well. But an electric current passes through gold very easily.
Gold jewelry
What is a karat of gold?
Gold's purity is measured in karats. The term "karat" harks back to the ancient bazaars where "carob" beans were used to weigh precious metals. 24 karat is pure gold, but its purity means it is more expensive and less durable than gold that is alloyed with other metals. Different alloys are used in jewelry for greater strength, durability and color range.
Gold is available as white or yellow gold, both of which are available in 14 or 18 karat. The difference between these two are as follows:
24 karat gold is pure gold.
18 karat gold is 18/24 gold (about 75% gold - three quarters gold).
14 karat gold is 14/24 gold (about 58% gold - a little over half gold).
12 karat gold is exactly half gold.
10 karat gold is 10/24 gold (only about 41% gold - less than half gold).
