No article having a gold alloy portion of less than one-twentieth by weight may be marked "gold-filled," but articles may be marked Lower limits are permitted in some countries. Having a gold alloy coating of less than 10-karat fineness may have any quality mark affixed. A quality mark may be used to show the quantity and fineness of the gold alloy. The term "gold-filled" is used to describe articles of jewelry made of base metal which are covered on one or more surfaces with a The jewelry industry, the common unit of measure is the pennyweight (dwt.) which is equivalent to 1.555 grams. One troy ounce is equivalent to 20 troy pennyweights. The basic unit of weight used in dealing with gold is the troy ounce. "Karat" should not be confused with "carat," a unit of weight used for precious stones. ![]() Incidentally, 14K gold is commonly used in jewelry manufacture. Thus, 14-karat (14K) gold indicates a composition of 14 parts of gold and 10 parts of other metals. "Karat" indicates the proportion of solid gold in an alloy based on a total of 24 parts. ![]() For example, a gold nugget containing 885 parts of pure gold and 115 parts of other metals, such as silver and copper, would be considered 885-fine. "Fineness" defines gold content in parts per thousand. The degree of purity of native gold, bullion (bars or ingots of unrefined gold), and refined gold is stated in terms of gold content. The material is then processed to remove the gold. The firehose blasts the sediment outcrop, washing away sand, clay, gravel and gold particles. Hydraulic placer mining at Lost Chicken Hill Mine, near Chicken, Alaska. The difference in density enables gold to be concentrated by gravity and permits the separation of goldįrom clay, silt, sand, and gravel by various agitating and collecting devices such as the gold pan, rocker, and sluicebox. Impure gold, as it commonly occurs in deposits, has a density of 16 to 18, whereas the associated waste rock (gangue) has aĭensity of about 2.5. The specific gravity or density of pure gold is 19.3 compared to 14.0 for mercury and 11.4 for lead. It is the most malleable and ductile of metals. Pure gold is relatively soft-it has about the hardness of a penny. Silver, copper, nickel, platinum, palladium, tellurium, and iron, with gold create various color hues ranging from silver-white to green and orange-red. Its chemical symbol Au isĭerived from the Latin word "aurum." In pure form gold has a metallic luster and is sun yellow, but mixtures of other metals, such as Gold is called a "noble" metal (an alchemistic term) because it does not oxidize under ordinary conditions. Prospectors worked stream sediments to find tiny nuggets that they would sell or trade for supplies. Gold nuggets: Small nuggets of gold obtained by panning. New World, and many gold and silver objects were melted and cast into coins and bars, destroying the priceless artifacts of the Indian culture. The Conquistadores plundered the treasuries of these civilizations during their explorations of the The gold in the Aztec and Inca treasuries of Mexico and Peru believed to have come from Colombia, although some undoubtedly was ![]() Recovered from this region during the reign of King Solomon (961-922 B.C.). Recent studies of the Mahd adhĭhahab (meaning "Cradle of Gold") mine in the present Kingdom of Saudi Arabia reveal that gold, silver, and copper were When these mines could no longer meet their demands, deposits elsewhere, possibly in Yemen and southern Africa, were exploited.Īrtisans in Mesopotamia and Palestine probably obtained their supplies from Egypt and Arabia. The region of the Upper Nile near the Red Sea and in the Nubian Desert area supplied much of the gold used by the Egyptian The ancient civilizations appear to have obtained their supplies of gold from various deposits in the Middle East. These elegant works of art were created by skilled craftsmen more than 3,500 years ago. Yielded a great variety of gold figurines, masks, cups, diadems, and jewelry, plus hundreds of decorated beads and buttons. The graves of nobles at the ancient Citadel of Mycenae near Nauplion, Greece, discovered by Heinrich Schliemann in 1876, Some of these items, called "Treasures of Tutankhamun," attracted more than 6 million visitors in six cities during a This young pharaoh ruled Egypt in the 14th century B.C. Particularly noteworthy are the gold items discovered by Howard Carter and LordĬarnarvon in 1922 in the tomb of Tutankhamun. Of ancient civilizations used gold lavishly in decorating tombs and temples, and gold objects made more than 5,000 years ago have been found in Egypt. ![]() Other elements, because it is beautiful and imperishable, and because exquisite objects can be made from it. Gold was among the first metals to be mined because it commonly occurs in its native form, that is, not combined with
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