Yigal Sharabi
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<div class="JNLC-copy"><span class="JNLC-title">gold, Silver And Platinum</span><br />
<p class="JNLC-SubTitle">Gold</p>
<p class="JNLC-copy"><span class="JNLC-copy">Gold is the chemical element with the symbol Au (from the Latin aurum) and atomic number 79. It is a highly sought-after precious metal which, for many centuries, has been used as money, a store of value and in jewelry. The metal occurs as nuggets or grains in rocks, underground "veins" and in alluvial deposits. Gold is dense, soft, shiny and the most malleable and ductile of the known metals. Pure gold has an attractive bright yellow color and is one of only two colored metal elements, the other being copper. All other metals are silver or gray.</span></p>
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Gold forms the basis for a monetary standard used by the International Monetary Fund (IMF) and the Bank for International Settlements (BIS). The ISO currency code of gold bullion is XAU. Modern industrial uses include dentistry and electronics, where gold has traditionally found use because of its good resistance to oxidative corrosion.</p>
<p class="JNLC-copy">Gold does not react with most chemicals, but is attacked by chlorine, fluorine, aqua regia and cyanide. Gold dissolves in mercury, forming amalgam alloys, but does not react with it. Gold is insoluble in nitric acid, which will dissolve silver and base metals, and this is the basis of the gold refining technique known as "inquartation and parting". Nitric acid has long been used to confirm the presence of gold in items, and this is the origin of the term "acid test," referring to a gold standard test for genuine value.</p>
<p class="JNLC-copy">Gold is the most malleable and ductile metal; a single gram can be beaten into a sheet of one square meter, or an ounce into 300 square feet. Gold leaf can be beaten thin enough to become translucent. The transmitted light appears greenish blue, because gold strongly reflects yellow and red. Gold readily forms alloys with many other metals. These alloys can be produced to increase the hardness or to create exotic colors.</p>
<p class="JNLC-copy">Gold is a good conductor of heat and electricity, and is not affected by air and most reagents. Heat, moisture, oxygen, and most corrosive agents have very little chemical effect on gold, making it well-suited for use in coins and jewelry; conversely, halogens will chemically alter gold, and aqua regia dissolves it by virtue of the elemental chlorine generated by this acid mixture.</p>
<p class="JNLC-copy">Because of the softness of pure (24k) gold, it is usually alloyed with base metals for use in jeweler, altering its hardness and ductility, melting point, color and other properties. Alloys with lower "k", typically 22k, 18k, 14k or 10k, contain higher percentages of copper, silver or other base metals in the alloy. Copper is the most commonly used base metal, yielding a redder metal. Eighteen carat gold containing 25% copper is found in antique and Russian jewelry and has a distinct, though not dominant, copper cast, creating an attractively warm color (rose gold). Fourteen carat gold-copper alloy is nearly identical in color to certain bronze alloys, and both may be used to produce police and other badges. Blue gold can be made by alloying with iron and purple gold can be made by alloying with aluminum, although rarely done except in specialized jewelry. Fourteen and eighteen carat gold alloys with silver alone appear greenish-yellow and are referred to as green gold. White gold alloys can be made with palladium or nickel. White 18 carat gold containing 17.3% nickel, 5.5% zinc and 2.2% copper is silver in appearance.</p>
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<p class="JNLC-copy"> Nickel is toxic, however, and its release from nickel white gold is controlled by legislation in Europe. Alternative white gold alloys are available based on palladium, silver and other white metals (World Gold Council), but the palladium alloys are more expensive than those using nickel. High-carat white gold alloys are far more resistant to corrosion than are either pure silver or sterling silver. The Japanese craft of Mokume-gane exploits the color contrasts between laminated colored gold alloys to produce decorative wood-grain effects.</p>
<p class="JNLC-SubTitle">Silver</p>
<p class="JNLC-copy">Silver is a chemical element with the symbol Ag (Latin: argentum) and atomic number 47. A soft white lustrous transition metal, it has the highest electrical and thermal conductivity for a metal. It occurs as a free metal (native silver) as well as various minerals such as argentite and chlorargyrite. Most silver is produced as a by-product of copper, gold, lead, and zinc mining.</p>
<p class="JNLC-copy">Silver has been known since antiquity. It has long been valued as a precious metal and used in currency, ornaments and jewelry, as well as utensils. Today, it is also used in photographic film, electrical contacts, and mirrors. Elemental silver is also used to catalyze chemical reactions.<br />
</p>
<p class="JNLC-copy">Silver has certain antimicrobial activity. In the past, dilute solutions of silver nitrate were used as disinfectants, though this has been supplanted by other treatments.</p>
<p class="JNLC-copy">Silver is a very ductile and malleable (slightly harder than gold) monovalent coinage metal with a brilliant white metallic luster that can take a high degree of polish. It has the highest electrical conductivity of all metals, even higher than copper, but its greater cost and tarnishability has prevented it from being widely used in place of copper for electrical purposes.</p>
<p class="JNLC-copy">Pure silver has the highest thermal conductivity, whitest color, the highest optical reflectivity (although aluminum slightly outdoes it in parts of the visible spectrum), and is a poor reflector of ultraviolet light. Silver also has the lowest contact resistance of any metal. Silver halides are photosensitive and are remarkable for the effect of light upon them. This metal is stable in pure air and water, but does tarnish when it is exposed to ozone, hydrogen sulfide, or air containing sulfur.</p>
<p class="JNLC-copy">A major use of silver is as a precious metal. Jewelry and silverware are traditionally made from Sterling silver an alloy of 92.5 % silver with 7.5% copper. Britannia silver is an alternative hallmark-quality standard containing 95.8 % silver, often used to make silver tableware and wrought plate. Silver is used in medals, denoting second place. Some high end musical instruments are made from sterling silver, such as the flute.</p>
<p class="JNLC-SubTitle">Platinum </p>
<p class="JNLC-copy">Platinum is a chemical element in the periodic table that has the atomic symbol Pt and an atomic number of 78. A heavy, malleable, ductile, precious, grey-white transition metal, platinum is resistant to corrosion and occurs in some nickel and copper ores along with some native deposits. Platinum is used in jewelry, laboratory equipment, electrical contacts, dentistry, and automobile emissions control devices.</p>
<p class="JNLC-copy">When pure, the metal appears greyish-white and firm. The metal is corrosion-resistant. The catalytic properties of the six platinum family metals are outstanding. For this catalytic property, platinum is used in catalytic converters, incorporated in automobile exhaust systems, as well as tips of spark plugs.<br />
</p>
<p class="JNLC-copy">Platinum's wear- and tarnish-resistance characteristics are well suited for making fine jewelry. Platinum is more precious than gold. The price of platinum changes along with its availability, but its price is normally slightly less than twice that of gold. In the 18th century, platinum's rarity made King Louis XV of France declare it the only metal fit for a king.</p>
<p class="JNLC-copy">Platinum possesses high resistance to chemical attack, excellent high-temperature characteristics, and stable electrical properties. All these properties have been exploited for industrial applications. Platinum does not oxidize in air at any temperature, but can be corroded by cyanides, halogens, sulfur, and caustic alkalis. This metal is insoluble in hydrochloric and nitric acid, but does dissolve in the mixture known as aqua regia (forming chloroplatinic acid).</p>
<p class="JNLC-copy">Platinum is an extremely rare metal, occurring as only 5 ppb in the Earth's crust. In 2005, South Africa was the top producer of platinum with almost 80% world share followed by Russia, Canada and Botswana, reports the British Geological Survey.</p>
<p class="JNLC-copy"><a href="/pages/metals"><img src='http://static1.shopify.com/s/files/1/0014/5692/files/Back1.png' alt='' /></a></a> </p>
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2008-07-17T09:39:50-04:00
gold-silver-platinum
351032
2008-07-17T09:39:50-04:00
145692
Gold, Silver & Platinum
2008-11-05T13:43:23-05:00
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<div class="JNLC-copy"><span class="JNLC-title">gold, Silver And Platinum</span><br />
<p class="JNLC-SubTitle">Gold</p>
<p class="JNLC-copy"><span class="JNLC-copy">Gold is the chemical element with the symbol Au (from the Latin aurum) and atomic number 79. It is a highly sought-after precious metal which, for many centuries, has been used as money, a store of value and in jewelry. The metal occurs as nuggets or grains in rocks, underground "veins" and in alluvial deposits. Gold is dense, soft, shiny and the most malleable and ductile of the known metals. Pure gold has an attractive bright yellow color and is one of only two colored metal elements, the other being copper. All other metals are silver or gray.</span></p>
<p class="JNLC-copy">
Gold forms the basis for a monetary standard used by the International Monetary Fund (IMF) and the Bank for International Settlements (BIS). The ISO currency code of gold bullion is XAU. Modern industrial uses include dentistry and electronics, where gold has traditionally found use because of its good resistance to oxidative corrosion.</p>
<p class="JNLC-copy">Gold does not react with most chemicals, but is attacked by chlorine, fluorine, aqua regia and cyanide. Gold dissolves in mercury, forming amalgam alloys, but does not react with it. Gold is insoluble in nitric acid, which will dissolve silver and base metals, and this is the basis of the gold refining technique known as "inquartation and parting". Nitric acid has long been used to confirm the presence of gold in items, and this is the origin of the term "acid test," referring to a gold standard test for genuine value.</p>
<p class="JNLC-copy">Gold is the most malleable and ductile metal; a single gram can be beaten into a sheet of one square meter, or an ounce into 300 square feet. Gold leaf can be beaten thin enough to become translucent. The transmitted light appears greenish blue, because gold strongly reflects yellow and red. Gold readily forms alloys with many other metals. These alloys can be produced to increase the hardness or to create exotic colors.</p>
<p class="JNLC-copy">Gold is a good conductor of heat and electricity, and is not affected by air and most reagents. Heat, moisture, oxygen, and most corrosive agents have very little chemical effect on gold, making it well-suited for use in coins and jewelry; conversely, halogens will chemically alter gold, and aqua regia dissolves it by virtue of the elemental chlorine generated by this acid mixture.</p>
<p class="JNLC-copy">Because of the softness of pure (24k) gold, it is usually alloyed with base metals for use in jeweler, altering its hardness and ductility, melting point, color and other properties. Alloys with lower "k", typically 22k, 18k, 14k or 10k, contain higher percentages of copper, silver or other base metals in the alloy. Copper is the most commonly used base metal, yielding a redder metal. Eighteen carat gold containing 25% copper is found in antique and Russian jewelry and has a distinct, though not dominant, copper cast, creating an attractively warm color (rose gold). Fourteen carat gold-copper alloy is nearly identical in color to certain bronze alloys, and both may be used to produce police and other badges. Blue gold can be made by alloying with iron and purple gold can be made by alloying with aluminum, although rarely done except in specialized jewelry. Fourteen and eighteen carat gold alloys with silver alone appear greenish-yellow and are referred to as green gold. White gold alloys can be made with palladium or nickel. White 18 carat gold containing 17.3% nickel, 5.5% zinc and 2.2% copper is silver in appearance.</p>
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<p class="JNLC-copy"> Nickel is toxic, however, and its release from nickel white gold is controlled by legislation in Europe. Alternative white gold alloys are available based on palladium, silver and other white metals (World Gold Council), but the palladium alloys are more expensive than those using nickel. High-carat white gold alloys are far more resistant to corrosion than are either pure silver or sterling silver. The Japanese craft of Mokume-gane exploits the color contrasts between laminated colored gold alloys to produce decorative wood-grain effects.</p>
<p class="JNLC-SubTitle">Silver</p>
<p class="JNLC-copy">Silver is a chemical element with the symbol Ag (Latin: argentum) and atomic number 47. A soft white lustrous transition metal, it has the highest electrical and thermal conductivity for a metal. It occurs as a free metal (native silver) as well as various minerals such as argentite and chlorargyrite. Most silver is produced as a by-product of copper, gold, lead, and zinc mining.</p>
<p class="JNLC-copy">Silver has been known since antiquity. It has long been valued as a precious metal and used in currency, ornaments and jewelry, as well as utensils. Today, it is also used in photographic film, electrical contacts, and mirrors. Elemental silver is also used to catalyze chemical reactions.<br />
</p>
<p class="JNLC-copy">Silver has certain antimicrobial activity. In the past, dilute solutions of silver nitrate were used as disinfectants, though this has been supplanted by other treatments.</p>
<p class="JNLC-copy">Silver is a very ductile and malleable (slightly harder than gold) monovalent coinage metal with a brilliant white metallic luster that can take a high degree of polish. It has the highest electrical conductivity of all metals, even higher than copper, but its greater cost and tarnishability has prevented it from being widely used in place of copper for electrical purposes.</p>
<p class="JNLC-copy">Pure silver has the highest thermal conductivity, whitest color, the highest optical reflectivity (although aluminum slightly outdoes it in parts of the visible spectrum), and is a poor reflector of ultraviolet light. Silver also has the lowest contact resistance of any metal. Silver halides are photosensitive and are remarkable for the effect of light upon them. This metal is stable in pure air and water, but does tarnish when it is exposed to ozone, hydrogen sulfide, or air containing sulfur.</p>
<p class="JNLC-copy">A major use of silver is as a precious metal. Jewelry and silverware are traditionally made from Sterling silver an alloy of 92.5 % silver with 7.5% copper. Britannia silver is an alternative hallmark-quality standard containing 95.8 % silver, often used to make silver tableware and wrought plate. Silver is used in medals, denoting second place. Some high end musical instruments are made from sterling silver, such as the flute.</p>
<p class="JNLC-SubTitle">Platinum </p>
<p class="JNLC-copy">Platinum is a chemical element in the periodic table that has the atomic symbol Pt and an atomic number of 78. A heavy, malleable, ductile, precious, grey-white transition metal, platinum is resistant to corrosion and occurs in some nickel and copper ores along with some native deposits. Platinum is used in jewelry, laboratory equipment, electrical contacts, dentistry, and automobile emissions control devices.</p>
<p class="JNLC-copy">When pure, the metal appears greyish-white and firm. The metal is corrosion-resistant. The catalytic properties of the six platinum family metals are outstanding. For this catalytic property, platinum is used in catalytic converters, incorporated in automobile exhaust systems, as well as tips of spark plugs.<br />
</p>
<p class="JNLC-copy">Platinum's wear- and tarnish-resistance characteristics are well suited for making fine jewelry. Platinum is more precious than gold. The price of platinum changes along with its availability, but its price is normally slightly less than twice that of gold. In the 18th century, platinum's rarity made King Louis XV of France declare it the only metal fit for a king.</p>
<p class="JNLC-copy">Platinum possesses high resistance to chemical attack, excellent high-temperature characteristics, and stable electrical properties. All these properties have been exploited for industrial applications. Platinum does not oxidize in air at any temperature, but can be corroded by cyanides, halogens, sulfur, and caustic alkalis. This metal is insoluble in hydrochloric and nitric acid, but does dissolve in the mixture known as aqua regia (forming chloroplatinic acid).</p>
<p class="JNLC-copy">Platinum is an extremely rare metal, occurring as only 5 ppb in the Earth's crust. In 2005, South Africa was the top producer of platinum with almost 80% world share followed by Russia, Canada and Botswana, reports the British Geological Survey.</p>
<p class="JNLC-copy"><a href="/pages/metals"><img src='http://static1.shopify.com/s/files/1/0014/5692/files/Back1.png' alt='' /></a></a> </p>
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