An Educational Guide to Gold for Kids

Facts about Gold

Gold, like no other metal, has a fascinating history and a special place in the world.  For thousands of years it has been used as an ornament of kings, a currency and standard for global currencies, and more recently, in a wide range of electronic devices and medical applications.

Gold's many unique properties have secured it a central role in history and human development. Gold is a remarkable, rare metal, with an unparalleled combination of chemical and physical properties. It is the only yellow metal and bears its name from the Old English word for yellow, 'geolu'. It is also the only metal that forms no oxide film on it's surface in air at normal temperatures, meaning that it will never rust or tarnish.

Gold's chemical symbol, Au, comes from the latin word for gold, aurum. In the Periodic Table of Elements, gold is classified as a transitional metal with the following characteristics:
  • Symbol: Au
  • Atomic number: 79
  • Atomic mass: 196.96655 amu
  • Number of protons/electrons: 79
  • Number of neutrons: 118
  • Melting point: 1,064.43°C (1,337.58°K, 1,947.97°F)
  • Boiling point: 2,807.0°C (3,80.15°K, 5,084.6°F)
  • Density @ 293°K: 19.32 grams per cubic centimeter
  • Crystal structure: cubic
  • oxidation states: +1, +3

Atomic Structure

Shells: 2,8,18,32,18,1

Like other transition metals gold's valence electrons, or the electrons it uses to combine with other elements, are present in more than one shell. Unusually for a metal, gold can also form compounds (aurides) in which its oxidation number is negative (-1). For example, gold can combine with cesium to form cesium auride, CsAu, and rubidium to form rubidium auride, RbAu. These are ionic compounds with non-metallic properties in which the Cs or Rb ions are charged +1 while the Au atoms are charged 1-.

Gold may be alloyed with various other metals to give it special properties. In its pure form, gold has a metallic luster and is sun yellow, but when mixed or alloyed with other metals, such as silver (Ag), copper (Cu), zinc (Zn), nickel (Ni), platinum (Pt), palladium (Pd), tellurium (Te), and iron (Fe), creates various color hues ranging from silver-white to green and orange-red. Usually, red, yellow and green golds are made by adding varying amounts of copper (Cu) and silver (Ag) to produce alloys of 10 to 14 carats. White golds have traditionally been made by alloying nickel (Ni), zinc (Zn) and copper (Cu) with gold, but more recently silver (Ag) and palladium (Pd) have replaced the zinc. These color variation treatments to gold are mostly used in jewelry.

Gold is found in nature in quartz veins and secondary alluvial deposits as a free metal or in a combined state. It is widely distributed although it is rare, being 75th in order of abundance of the elements in the crust of the Earth. It is almost always associated with varying amounts of silver; the naturally occurring gold-silver alloy is called electrum. Gold occurs, in chemical combination with tellurium, in the minerals calaverite and sylvanite along with silver, and in the mineral nagyagite along with lead, antimony, and sulfur. It occurs with mercury as gold amalgam. It is generally present to a small extent in iron pyrites; galena, the lead sulfide ore that usually contains silver, sometimes also contains appreciable amounts of gold. Gold also occurs in seawater to the extent of 5 to 250 parts by weight to 100 million parts of water. Although the quantity of gold present in seawater is more than 9 billion metric tons, the cost of recovering the gold would be far greater than the value of the gold that could thus be recovered.

Properties of Gold

Khrysos (Gold) is a child of Zeus; neither moth nor rust devoureth it; but the mind of man is devoured by this supreme possession. - 5th century Greek fragment.

The crystal structure for metallic gold is face centred cubic. This crystal structure contributes to gold's very high ductility since the lattices are particularly suitable for allowing the movement of dislocations in the lattice.

An unparalleled combination of chemical and physical properties make gold invaluable to a wide range of everyday applications. One of the most important of these properties is gold's virtual indestructibility. Gold is the most non-reactive of all metals. It is called a "noble" metal (an alchemistic term) because it does not oxidize under ordinary conditions, meaning that it will never rust and never tarnish.It will, however, dissolve in aqueous mixtures containing various halogens such as chlorides, bromides, or some iodides. It will also dissolve in some oxidizing mixtures, such as cyanide ion with oxygen, and in aqua regia, a mixture of hydrochloric and nitric acids.

Gold is only 2.5 on the Mohs scale of hardness - about the same as a fingernail. Pure gold is so soft and malleable that a strong man can squeeze it and shape it.  Therefore, gold could be used by artisans around the world for as far back as time can tell. 

Gold's physical properties of high electrical conductivity and chemical inertness make it an excellent and reliable conductor, particularly in harsh environments, where temperatures can range from -55°C to 200°C. The use of gold in circuitry ensures reliability of equipment operation, particularly in the vital activation of safety airbag mechanisms in motor vehicles or deployment of satellites and spacecraft.No other metal is as ductile or as malleable as gold. A single ounce of the metal can be drawn into a wire five miles long. Gold can be hammered into sheets so thin that light can pass through. High purity gold reflects infrared (heat) energy almost completely, making it ideal for heat and radiation reflection. Gold-coated visors protected astronauts' eyes from searing sunlight on the Apollo 11 moon landing. Gold is also an excellent conductor of thermal energy. It is used in many electronic processes to draw heat away from delicate instruments. For example, the main engine nozzle of the space shuttle uses a 35% gold alloy.


Annealing gold can make it both harder, and stronger. However, there is a point at which it can be overworked, which will eventually cause it to easily fracture.

Metals have a crystalline structure. When a metal is strained and distorted mechanically, the crystals become stressed and the metal hardens. To relieve this stress, and "relax" the structure, they must be heated to a temperature somewhat below the melting point. This is called annealing. Gold alloys must be cooled slowly after annealing.


The wear resistance is related to its surface hardness and age as well as to the actual metal. The annealed hardness of 9 & 18 kt golds are similar. 18, 14, 9 kt golds are considerably harder than 22 or 24 kt golds. Annealing softens them, and working (bending, twisting) tends to work harden metals (this explains why forged steel is much stronger than cast steel for the same alloy content).

Gold Colors

Gold is bright yellow and has a high luster. Apart from copper and caesium it is the only non white colored metal. Gold’s attractive warm colour has led to its widespread use in decoration.

The arrangement of outer electrons around the gold nucleus is the reason for the yellow color; to be precise, the transition of electrons from the d band to unoccupied positions in the conduction band.

Finely divided gold, like other metallic powders, is black; colloidally suspended gold ranges in color from ruby red to purple.Gold can mixed with other metals to give it different colors.

White gold is very popular right now. It can be in 18-karat or 14-karat gold (but not in 22-karat, as it is yellow gold). There are two basic types of white gold alloys: white gold mixed with nickel and white gold mixed with palladium. Nickel can be mixed with gold to create a white or gray color, but some people have an allergy to nickel. Palladium is another metal used to create white gold. Palladium is better but it costs more. To enhance the whiteness, almost all white gold is plated with rhodium, a shiny, white metal which is extremely hard. Depending on the amount of wear to a piece of jewelry, over time this rhodium plating may wear off, revealing the original metal color.

Copper creates pink and rose tones in gold.The more the copper, the deeper will be the effect.

Greenish shades are created by adding silver to gold w hile excluding copper from the mix. 18K green gold can be made from 75% gold and 25% silver. Cadmium can be incorporated to vary the tint of green. So combining 75% gold and 23% copper with 2% cadmium creates a light green, while 75% gold, 15% silver, 6% copper and 4% cadmium creates a dark green.

Rose gold and Green gold can be 18-karat or 14-karat but the color is stronger in the 14-karat alloys.

Purple gold. It is referred as amethyst or violet gold. Purple gold is obtained by mixing gold and aluminium in a certain fixed ratio. Gold content is almost 79% and therefore it is qualified to be referred to as 18K gold.

Blue gold is made as an inter-metallic compound between gold and indium . The gold gets a bluish hue color with this process.

Black gold is created using a few techniques. Electro-deposition using black rhodium or ruthenium is the first technique. Controlled oxidation of Carat gold containing cobalt or chromium can also be made to create black gold. Amorphous carbon is also used some times, with the Plasma Assisted Chemical Vapor Deposition process.

Chocolate gold is derived from a relatively new method created in Italy. Referred to as physical vaporization and deposition, it entails placing gold (usually rose-colored) in a suction compartment and blasting it with electrodes. This approach causes the gold's surface to oxidize in a controlled environment, resulting in the metal's color changing at a molecular level and producing a rich chocolate color. This permanently alters the metal and can only be removed by scraping off the outer layers

 Blue Gold 18K 75% Gold
25% Iron
 Yellow Gold 14K 58% Gold
4-28% Silver
14-28% Copper
 Yellow Gold 18K 75% Gold
10-20% Silver
5-15% Copper
 Yellow Gold 22K 92% Gold
4.2% Silver
4.2% Copper
 Green Gold 18K 75% Gold
11-15% Silver
13-0% Cadmium
 Red Gold 18K 75% Gold
25% Copper
 Sterling Silver 92.5% Silver
7.5% Copper
 White Gold-1 90% Gold
10% Palladium
 White Gold-2 75-85% Gold
8-10% Nickel
2-9% Zinc
 White Gold - 14Kt A 58.3% Gold
17% Copper
17% Copper
7.6% Zinc
 White Gold - 14Kt B 59% Gold
25.5% Copper
12.3% Nickel
3.2% Zinc
 White Gold - 18K 75% Gold
18.5% Silver
1% Copper
5.5% Zinc

Uses of Gold

Gold's special properties mean that it has a greater variety of uses than almost any metal. Gold conducts electricity, does not tarnish, is very easy to work, can be drawn into wire, can be hammered into thin sheets, alloys with many other metals, can be melted and cast into highly detailed shapes, has a wonderful color and a brilliant luster.

Gold has been prized by people since the earliest times for making statues and icons and also for jewelry to adorn their bodies. Intricately sculptured art objects and adornment jewelry have been uncovered in the Sumerian royal Tombs in southern Iraq and the tombs of Egyptian kings. Significant buildings and religious temples and statues have been covered with thinly beaten sheets of gold. Due to its rarity, gold has long been considered a symbol of the wealth and power of its possessor.

The following table gives recent demand for gold in tonnes.
Coins and bars
and dental

For information on gold supply click here.

Origins of gold

The relative average abundance of gold in our Solar System appears higher than can be made in the early universe, in stars, and even in typical supernova explosions. Some astronomers now suggest that neutron-rich heavy elements such as gold might be most easily made in rare neutron-rich explosions such as the collision of neutron stars. When two neutron stars collide, the resulting explosion produces massive amounts of gamma radiation. On 3rd June 2013 astronomers were able to observe such a collision. The unique glow that persisted for days at the location potentially signified the creation of substantial amounts of heavy elements - including gold. The amount of gold produced and ejected during the merger of the two neutron stars may be as large as 10 moon masses.

This is probably how gold originates. In the Milky Way, such gamma ray burst happens about every 100,000 years. The gold got to Earth when gold-containing meteorites bombarded the surface about 200 million years ago.

Gold is widespread in low concentrations in all igneous rocks and has been discovered on every continent on earth Estimates for Its abundance in the Earth's crust vary between .001 to 0.004 parts per million. In seawater there are about 0.00001 ppm. The average human body (70 kg) contains 0.2 mg of gold with the bone containing .016 ppm and the liver .0004 ppm.

It is 75th in order of abundance of the elements in the crust of the Earth.It occurs mostly in the native state, remaining chemically uncombined except with tellurium, selenium, and possibly bismuth. The element's only naturally occurring isotope is gold-197. Two types of deposits containing significant amounts of gold are known: hydrothermal veins, where it is associated with quartz and pyrite (fool's gold); and placer deposits, both consolidated and unconsolidated, that are derived from the weathering of gold-bearing rocks.

The origin of enriched veins is not fully known, but it is believed that the gold was carried up from great depths with other minerals, at least in partial solid solution, and later precipitated. The gold in rocks usually occurs as invisible disseminated grains, more rarely as flakes large enough to be seen, and even more rarely as masses or veinlets. Crystals about 2.5 cm (1 inch) or more across have been found in California. Masses, some on the order of 90 kg (200 pounds), have been reported from Australia.

Gold occurs mostly in the native state, remaining chemically uncombined except with tellurium, selenium, and possibly bismuth. Gold is almost always associated with varying amounts of silver; the naturally occurring gold-silver alloy is called electrum, an alloy of gold, platinum and silver, with trace amounts of copper and other metals. electrum has a warm, moonlight-tinged hue of pale to bright yellow. Electrum occurs naturally in the geographic region of ancient Lydia in Western Anatolia (present-day Turkey). Gold often occurs in association with copper and lead deposits, and, though the quantity present is often extremely small, it is readily recovered as a by-product in the refining of those base metals. Large masses of gold-bearing rock rich enough to be called ores are unusual. Gold also occurs in seawater to the extent of 5 to 250 parts by weight to 100 million parts of water. Although the quantity of gold present in seawater is more than 9 billion metric tons, the cost of recovering the gold would be far greater than the value of the gold that could thus be recovered.


The characteristic oxidation states of gold are +1 (aurous compounds) and +3 (auric compounds). Gold is more easily displaced from solution by reduction than any other metal; even platinum will reduce Au3+ ions to metallic gold.

Among the relatively few gold compounds of practical importance are gold chloride, AuCl; gold trichloride, AuCl3; and chlorauric acid, HAuCl4. In the first compound gold is in the +1 oxidation state, and in the latter two, the +3 state. All three compounds are involved in the electrolytic refining of gold. Potassium cyanoaurate is the basis for most gold-plating baths (the solution employed when gold is plated). Several organic compounds of gold have industrial applications. For example, gold mercaptides, which are obtained from sulfurized terpenes, are dissolved in certain organic solutions and used for decorating china and glass articles.

How much gold is there?

The best estimates available suggest that the total volume of gold ever mined up to the end of 2006 was approximately 158,000 tonnes, of which around 65% has been mined since 1950. Adding to this the number of tonnes that have been mined since 2006:

2007 2,478
2008 2,414
2009 2,589
2010 2,689

gives a total of 168,180 tonnes or 5,407,112,558 ounces. To visualise this imagine a single solid gold cube with edges of about 19 metres (about three metres short of the length of a tennis court). That's all that has ever been produced. The population of the world is 6,692,030,277 so there are 25 grams of gold per person on the planet.

Caveat The above calculation does not take into account the amount of gold lost each year in the form of industrial uses. Industrial and dental uses of gold account for about 10% of gold supply and most of this is used in quantities so small that it is not worth recovering. About .3% of the total above ground gold is probably lost each year in this manner.

At today's price of $1311.30 an ounce, the value of all the gold in the world is $7,077,108,684,520 or $1,058 for each person on the planet.

It is estimated that the total amount of gold yet to be retrieved from the Earth is about 100,000 tons.

A study by the UN in 2006 put the world's wealth at $125 trillion making the value of the world's gold about 6% of the total.

Welsh Gold

Welsh gold is one of the rarest metals in the world, and Welsh gold jewellery among the most highly valued.

There are 3 mines in Wales of which the most famous is Clogau which produces gold with a distinctive rose tint. Queen Elizabeth, the Queen Mother, Princess Margaret, the Prince of Wales, Princess Diana and Camilla the Duchess of Cornwall all wore/wear wedding rings fashioned from Clogau gold.

The wedding ring that Catherine Middleton wears is made of Welsh Gold.The gold was given to Prince William by The Queen shortly after the couple were engaged. It has been in the family's possession for some years and has been in the care of the Royal Jewellers.

In November 1981, the Royal British Legion presented the Queen with 36-grammes of 21 carat Welsh Gold. Part of this gold went into the making of the ring worn by Sarah, Duchess of York (1986). The wedding rings worn by The Earl and Countess of Wessex are made from Welsh gold, too (possibly from the piece presented in November,1981). The Prince of Wales wears his wedding ring under his signet ring.

Welsh gold can be identified by trace-element isotope analysis, but this is not practical for the retail customer, and the best way to buy it, as with all jewellery, is from a reputable jeweller.

Gold Mining

The search for gold used to mean wading in riverbeds to sift gold from the rushing water. Today, gold is mined from the earth, since most of the surface gold – known as alluvial gold – has been found. Gold mining today is largely a matter of technology. First, geologists use geology maps to look for favorable areas to explore. Ore deposits are not easy to find and many of the ones exposed on the surface have already been found. Geologists use the physical and chemical characteristics of the rocks they are looking for to zero in on prospective areas. Once favorable geology is established, remote sensing, airborne and ground geophysics and geochemistry are used to outline targets for drill testing.

Drilling at these sites brings up rock samples from various locations. These samples are analyzed to determine if any gold exists there, the size of the deposit, and the quality of the gold. Using this information, mining engineers determine if enough gold is under the surface to make the mining worthwhile; the type of mine needed; the physical obstacles to getting to the gold; and what impact a mine would have on the area's wildlife and environment. If the gold is close to the surface, the engineers will design an open-pit mine; if the gold is buried deeply, they will plan an underground mine.

Before the gold can be mined, an infrastructure must be created. Even if the gold is close to the surface, the simplest open-pit mine can take up to a year to build. In fact, the time between discovering gold and actually bringing it out of the earth can be up to five years. Since mines are often in remote locations, an entire infrastructure – roads, administrative offices, equipment storage areas, even towns, schools and medical facilities – must be built. The plans for the mines must be given the green light by a number of authorities at each level of government. Also, the mining company must put aside money for reclaiming the land once the gold is mined. In all, the preparation process can end up costing hundreds of millions of dollars – before a single ounce of gold is mined.

Ore samples are taken and examined for the metallurgical quality of the gold in order to determine the appropriate processing technique required to remove the gold. The mine site infrastructure includes a processing area where the ore is crushed and undergoes various processes depending on the nature of the associated minerals and then the loose rock is sent to the appropriate processing location. The process for low-grade ore is relatively simple: a cyanide solution is applied to the heap, dissolving the gold, which is then collected. High-grade ore, on the other hand, heads to the grinding mill for a more extensive process. There are several different ore types which require different processes for optimal recovery of the gold. For example: 1. Oxide ore goes directly to the leaching circuit, where cyanide dissolves the gold. 2. Refractory ore, which contains carbon, is roasted at 1000 degrees Fahrenheit, burning off the sulphide and carbon, then heads to the leaching circuit. 3. Sulphide refractory ore, which does not contain carbon, is oxidized in an autoclave in order to separate the sulphide safely, and in an environmentally friendly manner, from the ore, which then enters the leaching circuit. In the leaching circuit, the gold is extracted from the solution and deposited onto activated carbon, from which the gold is then chemically stripped. The impure gold is then melted into dorι bars, which are about 90 percent pure gold. These bars are usually shipped to a refinery where they undergo further processing.

The refining process strips out the remaining impurities from the gold, which is either recycled scrap being upgraded or gold destined to become bullion bars. In the first step, crude gold is melted and treated with chloride, converting remaining metals to chlorides that will drift off the gold. The resulting 99.5 percent pure gold is cast into electrodes known as anodes, which are put into an electrolytic cell. After a current is passed through the cell, the end product is 99.99 percent pure gold.

After a number of years, the gold reserves in a mine will be exhausted. In the old days, a spent mine would be boarded up and abandoned, but nowadays a reclamation project returns the land, as much as possible, to its previous natural state.

Jewelry and Money

Jewelry and money have always been closely related. Historically precious metals were used as a store of value and tied around the owner's neck or wrist when traveling. Thus if the caravan was attacked by bandits, the travelers could abandon their bags and flee with their gold. Eventually people noticed that gold and silver looked attractive when worn this way, and these metals started to be used an jewelry. With the development of banking holding money in this way became less prevalent. although even today many people in Asia and the Middle East keep jewelry in place of fiat currency.

The recognition that precious metals have a monetary component can be seen in the fact that they all have their own ISO 4217 currency code.

Gold - XAU

Silver - XAG

Platinum - XPT

Palladium - XPD

Gold as an Investment

Throughout history gold has been a store of value. According to the Talmud you should keep one-third of your assets each in land, 'business interests', and gold. This idea has a modern equivalent in the Permanent Portfolio theory which prescribes a mix of 25% each of Treasury bills, long bonds, stocks and gold. Most pension funds invest only in equities and bonds, with small allocations to property and cash. However, in recent years concerns have grown over the risks inherent in these asset classes, leading to increased interest in gold by hedge funds.


An advantage of coins is that they are easy to sell anywhere in the world. People will buy coins without assaying them which is not the case with gold bars. The premium over the spot price of gold is somewhere between 3-6% for a one ounce coin, although higher for smaller coins. For a 1/20 ounce coin the premium could be as high as 40%.



The premium over the spot price for bars is around 2%. Unfortunately it is easy to produce fake gold bars using tungsten, which has the exact same density as gold making a fake bar salted with tungsten indistinguishable from a solid gold bar by simply weighing it. Because tungsten is brittle it is hard to do this with coins.


In Asia and the Middle East many people buy jewelry as an investment. It is possible to buy 21K, 22K and 23K gold jewelry at around 5% over the spot price.

Exchange Traded Funds

It is possible to buy shares in a gold ETF called GOLD, which has the ticker symbol GLD. The shares are priced at the mid point between the buying and selling price of the spot price of gold.

IAU, SGOL and PHAU are 3 other gold based ETFs similar to GLD. PHAU is based in London.

UGL replicates, net of expenses, twice the performance of gold bullion.

DGZ is an ETN that shorts the gold price. DZZ double shorts gold.

GDX tracks the AMEX Gold Miners index.

There are several disadvantages to this way of owning gold.   While the expenses of the gold ETF are low, the Trust will have to sell part of its gold stores to pay these expenses.  Thus, over time, the fractional amount of physical gold represented by each share will decrease. Indeed it is not clear how much, if any, gold GLD actually possesses as it is never audited.

The Central Fund of Canada,(CEF) is based in Canada and holds gold and silver on behalf on investors. Its holdings of gold are audited and it trades at a premium over its NAV, unlike to ETFs.

Futures and Options

The principle futures contracts are YG, YI, ZG GC and SI.You can also buy and sell options on these contracts.

Spot price: $1311.30 an ounce

Total amount of gold in the world: 168,180 tonnes

Total value of all the gold in the world: $7,090,346,697,305

Value of world's gold per person: $1,060

Testing Gold

Properties of Gold

Gold Colors

Uses of Gold

Origins of Gold


How much gold is there?

Gold as an investment